I did it like this in my mind when I was first learning how as a child, a teacher told me that it was the wrong method and I was wrong. So I constantly struggled as a child. The American School System is ridiculous
Jose A that's no the case at all, the reason is that some questions specifically want you to use a certain method and doing that will help build memory
I've always done it like that. I'm not any good at doing math in my head though. The numbers often "get lost" in my head and I have to start over from the beginning several times.
There are methods you can use to cement numbers into your memory. A good way is the mnemonic major system, which allows you to convert numbers to words. That way you can visualize them. For example, I might see 3021 as "Miss net", or a net with a pink bow on top (to show that it's a lady, or a "miss"). It's a silly image, but memorable. If I know the system well then I can convert it back to a number without difficulty.
Sometimes you can make other associations too. Like "31616", for example. I see 316 as the well-know bible verse "John 3:16", and then the 16 just repeats after that.
*2 -> double number, usually easy *3 -> annoying, try to triple in your head using the method in this video *4 -> double number, then double again *5 -> times number by 10, then halve it *6 -> triple number, then double it *7 -> the worst, times by 5 then add 2 lots of the number *8 -> double number 3 times *9 -> times number by 10, then take one lot of the number off *10 -> move decimal point right by 1
I can do the math in my head but its the memory for me that feels like Im fighting for my own will power for mercy, this is a skill that can be developed and it takes a lot of consistency//practice. I call it the inside work
you can also split up the multiplier in your head so you don't have to carry as often, and then add the different totals. for example, instead of 423 * 4, you could do 423 * 2 = 846 to 846 *2=1692 , doing this while grouping bigger numbers together can really simplify everything.
I’m such a math nerd. I couldn’t sleep and searched this up because I’ve always wanted to be good at this and thanks to this video, I now know how to do math mentally at literally 12:14 am😂
Thank you! Now I can complete the multiplication part of my brain training games. We use calculators for everything and forget we all actually have a calculator in us that we are not using because we rely on machines all the time. They never taught me how to do this at school 30 years ago. We are never to old to learn something new!
Man all my math teachers got mad when ever we did mental math, and told us it was bad to do it, because they wanted to cut cheating. Now I’m stuck here trying to learn it way older than I should.
It only works if you get the remainder as zero after dividing the number by 2. For me, this works better, Divide by 2 and add a zero to your answer only if the remainder is zero. If it isn't, add a 5 to your answer before the decimals come in if that makes sense!
When I was in second grade I was sick the day the class learned to do long multiplication. Our teacher gave us a multiplication question with a 12 digit number. It was the first time I had ever tried a multiplication problem like that. I did the whole thing in my head. This is exactly the method that I used. I just did it naturally. When our teacher went around the class she looked at my paper and asked if I could show the class how I did it. I of course had no idea how I did it so I said no, lol. But I can look back on that as being a defining moment in my relationship with mathematics. Missing that lesson on long multiplication (and many others simply due to attention deficit) was best possible outcome. For me, the best way to learn is and always has been to be presented with a challenging problem and use the rules to find my own way. If I can't find the solution, it's because I am missing a rule; but by finding it myself I cement it into my memory forever. Over the years I came up with an algorithm. If you break down a problem into 10's, 2's, 1's, multiplication of single-digit numbers and addition or subtraction it becomes simple. For instance, multiplying by 5 is simply multiplying by 10 and dividing by 2. Also, even numbers are easier than odd numbers.
I'm 52, came across one of your videos that looked interesting about 30 mins ago. and i'm gobsmacked. how the hell are these methods not taught in school ? jeeez you just turned maths on its head, for me. great stuff. thanks
It surprisingly gets easier with even a little practice. I watched several of these videos earlier then when watching these problems and processes the answers came more readily.
2 am and the first problem he did I thought it left to right, but continued to watch the video to see if he taught any other carpenters math, stay healthy
That's weird, I've developed over the years, pretty much the same method of calculating in my head. I just tend to group and multiply the numbers that don't need anything carried over. For example when multiplying 21613 by 5, I would just begin by multiplying 21 by 5 to get 105, instead of 2 by 5 then 1 by 5, just cutting corners, if you will.. I also found that it's easier to multiply in my head, large numbers that are closer to the next hundred or thousand (100's and 1000's are obviously much more easy to multiply than most random given numbers) by multiplying the difference between the original number and the rounded number, by the multiplicand ... Then subtracting that product from the product of the rounded number and the multiplicand ... For instance if I wanted to multiply 19875 X 4 in my head, I would see that 19875 is 125 away from 20000 which is much more easily multiplied by 4, and would be 80000, and that difference of 125 multiplied by 4 is 500, which subtracted from 80000 would give you 79500, which is the product of 19875 X 4. It ends up coming in handy a lot when calculating in my head.
If you replace the multiplier 5 by 10 * 0.5, you can add a zero to multiply by 10, and then divide by 2 to multiply by 0.5. You can divide by 2 by grouping the dividend into even number groups and dividing individually, minding carry. Example 1: 5 * 21613 = 0.5 * (10 * 21613) = 0.5 * 216130 216_130 108_065 Above, instead of multiplying, we halve each group and combine the results to produce the answer: 108065 Example 2: 5 * 1933 = 0.5 * 19330 19_330 09_165 Here, for the sake of example, we have the odd number 19 to be divided by 2, the quotient being 9 with a remainder of 1: 2 * 9 = 18 19 - 18 = 1 You will never have a bigger remainder than 1 because we're dividing by 2 and every second number is even. In case we encounter odd dividends like this, we have to add the half of that remainder to the next number, which is the 1 in 330 / 2 = 165. This half is of course 5, which is 0.5 relative to the remainder (thousands), but 5.0 in the next position (hundreds). So 165 becomes 665: 19_330 09_165 09_665 5 * 1933 = 9665 Don't forget zeros when you construct the final answer. Example: 5 * 1262017253801896 = 0.5 * 12620172538018960 12620172538018960 12_620_172_538_018_960 06_310_086_269_009_480 ^ ^ ^ 5 * 1262017253801896 = 6310086269009480
+jl7986 That comes with practice. I like to split up or chunk the numbers in my head, by putting in commas just like I would on paper. I would look at 21613 x 5 as 21,613 x 5, and I'd work from left to right because that's how I read. 21 x 5 is 105 and 613 x 5 is 3065. But I've got to carry the "3" to the thousands place immediately to the left of the comma. I'd "see" the number as105,(3)065. I keep the three separate in parentheses so I automatically know to carry it to the left. 105,(3)065 = (105+3),065 = 108,065. This is known as "melding" numbers, and is covered in Ronald Doerfler's book, "Dead Reckoning: Calculating Without Instruments".
@Floofy shibe you cannot divide both the sides by zero Its like multiplying on both sides by infinity And you know my friend that infinity is not defined And also 0/0 is indeterminant
I learned to do all my math without a calculator as a child. Now I use a calc because they are everywhere. It feels good to know that I was never stumped by a math problem without one though.
I would always do my maths mentally because I found it easier and less time construction given the amount of class time we got to work each day, but one thing I ran into when multiplying numbers with more than 7 digits including decimals places is keeping track of the zeros and decimal places
My College Algebra 101 Final is tomorrow and YOU just helped me discover that my mind has for some reason of another always wanted to do multiplication this way! I just kept ignoring it to do what our professor was telling us how we should do multiplication. Thank you so much for the help! I feel like I don't need to depend on a calculator anymore!
I get how to forward carry when the numbers equal low but what happens when your forward carry totals more than 10. Example 327,891 x 4. 3 x 4 = 12 (no need to forward carry as next one is a 2) so number is 12..... 2 x 4 = 8 (but need to forward carry as 7 next, 7 x 4 is 28....how do I carry forward 2 into the 8) do I have to jump one step back and make the original 12 a 13? Cheers Paul
You are making hard work of it mate, 31616 x4 = 4x3 = 12. 4x16 = 64 and the last 2 digits are 64. ans 126464. you multiply 2 numbers to avoid carries. 21613 x 5 x 2 = 10. 5 x 16 = 80. and 5 x 13 = 65 ans 108065.
Joss Cues You are right, but that's assuming you know off the top of your head that 16x4 is 64 (if you don't, you then have to pre multiple 16x4 in your head (while you are still thinking about the first part of the equation) and then get the answer to 16x4 = 64 while remembering the next part of the equation) (and you have to remember that number for the rest of the equation) and then you have to remember the next 3 equations you wrote out, this method works for EVERY SINGLE NUMBER you don't have to know anything except your basic multiplication (12x12), and the next number you are looking at.
Same here. It gets harder with bigger numbers though... x * y where x and y are both larger than, say, 15 gets exponentially harder. Or rather, it requires exponentially better short-term memory for numbers. Which is exactly my problem...
I have a sharp memory when it comes to math and science and programming and grammar and stuff involving learning but when people ask me unimportant stuff I don't remember at all.
It's been a few years since I visited this video and I've practiced a lot. I find that I'm better off if I look away from the numbers while I'm calculating, so clearly my memory has improved.
When I was younger, i'm still 11, but I did this when I started 2nd grade. My teacher would say " Young man, did you cheat?" I'd say " I dare not, if I did so i'd get abuse by my parents!".
Cool way of looking at it. I'd add up all the numbers in my head because it was too hard for me to carry constantly, but this solves my problems. Nice.
Good video, if I can suggest to leave more of a lapse time when asking viewers to try the mathematics in their head. Before you continue on with the answer!
I am relaxed now because 2.1k subscribers are having mental math problem . 😀. I am not alone ( I thought I am idiot ) in the world of numbers . Bow down to the person who shared this solution . THANK YOU SIR .
Mini Noah the Worm the two 1s in the "31616" equal two. Then you multiply that by the 3 in the "31616" and you get 6. The other two 6s put next to the third six that we got from the addition and subtraction that we recently got make 666. Therefore, SATAN
Thank you so much, this isn't just mental math, I would suggest whoever is starting with this starts with doing it on paper still and than go to mental math.
I just started practicing the Trachtenberg Method and I see people say how everything someone learned in class can be sumed up in a 5 minute video but this is true. It is so much easier and faster for me than what I learned at school. So all the years learning that specific way and this method I just found out is so much better for me, sad.
Ex. 3492*38 ---> 3492(30+8) --- distributive property ---> 3492(30)+3492(8). It's more unwieldy to store separate values in your head and then proceed to add them, though.
Adeeb Mahmud ok so basically you do the exact same thing except do it however many digits over again and add zeroes to each consecutive number you come up with and then add them all in your head
I'm in trouble.626 times 7. 6x7 = 42 , remember the 42. 7x2 = 14 , remove the 2 from remembered 42 and add a 1 from the 14 = 3. So right now we have a 434. remember that. Another 6x7 = ... Oh crap, I just solved my problem -_-.. Typed for nothing..
karim786owais Hey Karim, Thanks for the reply little man! It's a pretty cool thing if you know math, seems you have it going pretty well :). I'm not into math that much, It seemed pretty cool to me to learn a new may of math. Curiosity really. What I'm more interested in is that children should learn on how to write English in a way that everybody could fully understand. In a respectful way, even. Ugh, what the heck, just don't tell me what to do kid. Typed for nothing..
I think it's better to keep track of the trailing zeros the whole way, so as not to get confused. With 626 x 7, when you multiply 6 x 7 for the first digit, you really are multiplying 600 x 7. So you drop the two zeros, multiply 6 x 7, and add the two zeros back on to the end of the number. Now you have 4,200. Then multiply the middle digit (2) x 7, which is really 20 x 7, due to the "2" being in the tens column. Drop the zero and add it back on at the end of the multiplication. 2 x 7 = 14, and add the zero back. You get 140. Add 140 to the original 4,200, by adding from left to right. 4,200 + 100 is 4,300, + 40 is 4,340. Then add the final 6 x 7: there are no zeroes to drop. You have 42. 4,340 + 40 = 4,380 + 2 = 4,382.
When I was in proper practice of mathematics I could do a lot of calculus in my head. I once solved a practical design problem mentally in around two minutes, and then spent eighteen months working out the proof, although I did do other work too at the time. The company that was employing me at the time could not understand how it took me so long to do the proof,but most of them didn't understand how I was doing it anyway. A work colleague then tried to present my work as his own, but as maths is very closely related to magic he had an accident on the way to the institute where he was going to show the proof and died. Maths is a powerful thing, and should not be confused with arithmetic.
Ty very much I was really bad at maths used to get D Everytime but I watched Maths Videos on UA-cam and got better first I learned the algorithm and carrying I got good at it then learned Cros Multiplying Now This One For Big Numbers I have learned more here then school tyvm
its not. It's the same as reading backwards, your brain is trained in one direction; I'm not saying which method is natural, there's no "natural" method. We use latin alphabet, which is read left to right; so left to right makes "natural" sense for us (who read left to right that is). Mathematics is done with arabic numbers; and arabic is right to left... those methods were designed by people who were trained with right to left language background; the brain works with patterns and once its used to something; it becomes natural.
I did it like this in my mind when I was first learning how as a child, a teacher told me that it was the wrong method and I was wrong. So I constantly struggled as a child. The American School System is ridiculous
Jose A that's no the case at all, the reason is that some questions specifically want you to use a certain method and doing that will help build memory
🤦Teachers should encourage different types of learning and solving
This isn't only the case for American sch. system)) hi from Uzbekistan
No it's not, only you teacher is
And so the Indian system is too
Stop flicking through the comments and concentrate!
Splash Toons no
Splash Toons Never
i dont wanna concentrate. o.o
That cought me off guard XD
Best comment so far
I've always done it like that. I'm not any good at doing math in my head though. The numbers often "get lost" in my head and I have to start over from the beginning several times.
same
I can't picture anything in my head??? How is that possible??
Same
@@boperez2841 I can't do it too 😂 some people are better at it tham the others
I'm 19 and looked for these videos because I've been noticing a decrease in my memory skills
Same
I was good at math and I've started to slow down and drop
saaaaaaame!
Same lol I smoke too much weed hahaha
@@BobGnarly420 It's not the weed. It's your habits. Challenge yourself daily and lower electronic consumption. It's obliterating your attention span.
@@nerat123 nah ye i kno tha just I cba tryna be relatable ini😂
I have never gotten in the habit of writing down my maths and this trick is exactly how I have thought math was always done in your head.
It's great, except I am having trouble remembering the original number. I suppose it'd get easier with practice.
Kathrin Turner ... welp I guess I'm more STUPID
Kathrin Turner you should say to yourself that practice makes perfect.
You are right Kathrin turner
There are methods you can use to cement numbers into your memory. A good way is the mnemonic major system, which allows you to convert numbers to words. That way you can visualize them. For example, I might see 3021 as "Miss net", or a net with a pink bow on top (to show that it's a lady, or a "miss"). It's a silly image, but memorable. If I know the system well then I can convert it back to a number without difficulty.
Sometimes you can make other associations too. Like "31616", for example. I see 316 as the well-know bible verse "John 3:16", and then the 16 just repeats after that.
*2 -> double number, usually easy
*3 -> annoying, try to triple in your head using the method in this video
*4 -> double number, then double again
*5 -> times number by 10, then halve it
*6 -> triple number, then double it
*7 -> the worst, times by 5 then add 2 lots of the number
*8 -> double number 3 times
*9 -> times number by 10, then take one lot of the number off
*10 -> move decimal point right by 1
Ya that's not how you multiply by five, that's how you divide by five.
@@DaronKabe That's an oof from me
Am I the only one or does this look like gibberish to anyone else. What is the context of this?
I do it for the most part... i'm 14
@@psychopathinthemaking how to times numbers by 2, 3, 4, 5, 6 etc..
I can do the math in my head but its the memory for me that feels like Im fighting for my own will power for mercy, this is a skill that can be developed and it takes a lot of consistency//practice. I call it the inside work
Me: **tries to multiply with my mind**
My childish mind full of dinosaurs and robots fighting: *"Allow me to introduce myself"*
Q
@@oofnoob5164 U GOT AN IQ MIND XD
@@anxerz8792 thanks ?
@@anxerz8792 im a cuber..if u dont know what cuber means u can search in google
@@anxerz8792 cubing made my muscle memory good
you can also split up the multiplier in your head so you don't have to carry as often, and then add the different totals. for example, instead of 423 * 4, you could do 423 * 2 = 846 to 846 *2=1692 , doing this while grouping bigger numbers together can really simplify everything.
Ooh interesting thank you for that
Wow cool! Thanks!
30 times 3 is 90
21 times 3 is 63
9063 thats how i do it
That's how I did it too
Wow that's actually really cool
Also 1616 x 4
16 x 4 = 64
Since there are two 16's you can just say 6464
Darth Geros I did the column multiplication but in my head
Darth Geros I really like your our method it is very cool
I’m such a math nerd. I couldn’t sleep and searched this up because I’ve always wanted to be good at this and thanks to this video, I now know how to do math mentally at literally 12:14 am😂
Lol
Hahaha
It's 12:14 am en for me
*12:14 am too early for me who stays up all night just trying to do sums in his head😅
Tell me why my dumb self clicked the time thing
Thank you! Now I can complete the multiplication part of my brain training games. We use calculators for everything and forget we all actually have a calculator in us that we are not using because we rely on machines all the time. They never taught me how to do this at school 30 years ago. We are never to old to learn something new!
Yes you are right 😀
Yeah
awkward moment when you get the first question wrong
Ahmed Adem same I got the 9 thousand part but not the rest
Lmao I didn’t even get a chance to work it out because he gave me the answer too fast
@@Amieee WWWOOOWWWWWWW!!!!1 IMPRESIVE
Ali Al-Rashid !!!!!!!!111
@@Amieee Do you know me ?
Man all my math teachers got mad when ever we did mental math, and told us it was bad to do it, because they wanted to cut cheating. Now I’m stuck here trying to learn it way older than I should.
When I mentally multiply by 5 I do something different - I divide by 2 and add a zero to my answer...
5896*5 = 29480
I add a zero and then divide by two lol that way I don’t ever have to deal with decimals
@@ellevasc i square it then multiply by 10 then find the square root then divid by two
@@Michael-st9ky add an 0 and divide it by 2
It only works if you get the remainder as zero after dividing the number by 2. For me, this works better,
Divide by 2 and add a zero to your answer only if the remainder is zero. If it isn't, add a 5 to your answer before the decimals come in if that makes sense!
I've been doing it this way for years. Works great! It helps if you have a good memory.
When I was in second grade I was sick the day the class learned to do long multiplication. Our teacher gave us a multiplication question with a 12 digit number. It was the first time I had ever tried a multiplication problem like that. I did the whole thing in my head. This is exactly the method that I used. I just did it naturally. When our teacher went around the class she looked at my paper and asked if I could show the class how I did it. I of course had no idea how I did it so I said no, lol. But I can look back on that as being a defining moment in my relationship with mathematics. Missing that lesson on long multiplication (and many others simply due to attention deficit) was best possible outcome. For me, the best way to learn is and always has been to be presented with a challenging problem and use the rules to find my own way. If I can't find the solution, it's because I am missing a rule; but by finding it myself I cement it into my memory forever. Over the years I came up with an algorithm. If you break down a problem into 10's, 2's, 1's, multiplication of single-digit numbers and addition or subtraction it becomes simple. For instance, multiplying by 5 is simply multiplying by 10 and dividing by 2. Also, even numbers are easier than odd numbers.
I'm 52, came across one of your videos that looked interesting about 30 mins ago.
and i'm gobsmacked. how the hell are these methods not taught in school ?
jeeez you just turned maths on its head, for me. great stuff. thanks
Thry do in middle school 4 me in 2020
the fact that we are not even learing this in school i am having a hard time with multplicatoin but now i really want to learn it to master this trick
I'm from Pakistan and we are tired of old procedures, This is brilliant way to do!
Rolls Up I am from 🇵🇰 too
Namra Diy yiur
I'm pakistani too😊
I love when I realize that this is the way that I always have done it xD
Thank you, I never was good at math. Your tips realy helped me getting this done easily.
It surprisingly gets easier with even a little practice. I watched several of these videos earlier then when watching these problems and processes the answers came more readily.
2 am and the first problem he did I thought it left to right, but continued to watch the video to see if he taught any other carpenters math, stay healthy
That's weird, I've developed over the years, pretty much the same method of calculating in my head. I just tend to group and multiply the numbers that don't need anything carried over. For example when multiplying 21613 by 5, I would just begin by multiplying 21 by 5 to get 105, instead of 2 by 5 then 1 by 5, just cutting corners, if you will..
I also found that it's easier to multiply in my head, large numbers that are closer to the next hundred or thousand (100's and 1000's are obviously much more easy to multiply than most random given numbers) by multiplying the difference between the original number and the rounded number, by the multiplicand ... Then subtracting that product from the product of the rounded number and the multiplicand ... For instance if I wanted to multiply 19875 X 4 in my head, I would see that 19875 is 125 away from 20000 which is much more easily multiplied by 4, and would be 80000, and that difference of 125 multiplied by 4 is 500, which subtracted from 80000 would give you 79500, which is the product of 19875 X 4. It ends up coming in handy a lot when calculating in my head.
If you replace the multiplier 5 by 10 * 0.5, you can add a zero to multiply by 10, and then divide by 2 to multiply by 0.5. You can divide by 2 by grouping the dividend into even number groups and dividing individually, minding carry.
Example 1:
5 * 21613 = 0.5 * (10 * 21613)
= 0.5 * 216130
216_130
108_065
Above, instead of multiplying, we halve each group and combine the results to produce the answer: 108065
Example 2:
5 * 1933 = 0.5 * 19330
19_330
09_165
Here, for the sake of example, we have the odd number 19 to be divided by 2, the quotient being 9 with a remainder of 1:
2 * 9 = 18
19 - 18 = 1
You will never have a bigger remainder than 1 because we're dividing by 2 and every second number is even. In case we encounter odd dividends like this, we have to add the half of that remainder to the next number, which is the 1 in 330 / 2 = 165. This half is of course 5, which is 0.5 relative to the remainder (thousands), but 5.0 in the next position (hundreds). So 165 becomes 665:
19_330
09_165
09_665
5 * 1933 = 9665
Don't forget zeros when you construct the final answer.
Example:
5 * 1262017253801896 = 0.5 * 12620172538018960
12620172538018960
12_620_172_538_018_960
06_310_086_269_009_480
^ ^ ^
5 * 1262017253801896 = 6310086269009480
jl7986 Samee
That's how I was taught in 4th grade
+jl7986 That comes with practice. I like to split up or chunk the numbers in my head, by putting in commas just like I would on paper. I would look at 21613 x 5 as 21,613 x 5, and I'd work from left to right because that's how I read. 21 x 5 is 105 and 613 x 5 is 3065. But I've got to carry the "3" to the thousands place immediately to the left of the comma. I'd "see" the number as105,(3)065. I keep the three separate in parentheses so I automatically know to carry it to the left. 105,(3)065 = (105+3),065 = 108,065. This is known as "melding" numbers, and is covered in Ronald Doerfler's book, "Dead Reckoning: Calculating Without Instruments".
@@DaronKabe bruh
math masters 1×300 = 300
Quick matfs
Easy peasy my mother macaroni is cheesy lol😂🤣
wow i didn't know that XD
Army 💜💜
@Floofy shibe you cannot divide both the sides by zero
Its like multiplying on both sides by infinity
And you know my friend that infinity is not defined
And also 0/0 is indeterminant
I learned to do all my math without a calculator as a child. Now I use a calc because they are everywhere. It feels good to know that I was never stumped by a math problem without one though.
Excellent Thank you Sir
2:03 it's just like skip counting!!😮😮😮😮😮😮cool trick!
omfg thank you!! this is much easier than mentally going from right to left! I got it on my second try :D
I just learned something that i didnt learn in the 11 years i've been in school. Thank you .
Schools are just waste of time..
I would always do my maths mentally because I found it easier and less time construction given the amount of class time we got to work each day, but one thing I ran into when multiplying numbers with more than 7 digits including decimals places is keeping track of the zeros and decimal places
^consuming**
This method helps me keep track of both the digit placement and decimal placement, I’m not sure why tho
My College Algebra 101 Final is tomorrow and YOU just helped me discover that my mind has for some reason of another always wanted to do multiplication this way! I just kept ignoring it to do what our professor was telling us how we should do multiplication. Thank you so much for the help! I feel like I don't need to depend on a calculator anymore!
Your voice is so soothing and easy to listen to.
I just tried this with decimals, it works great too! Why didnt they ever teach us this I'm school?
Teachers: did u cheat?
Because you need to show the work 😂😂
I needed this my grades are low
+Victoria Medeiros what grade are u in and what are your grades like?
+Laolu why should I tell ypu
Victoria Medeiros I was just wondering, jeez, don't get so defensive, if you don't want to tell me u don't have to.
+Laolu Arogundade calm down wow!
Victoria Medeiros Are u fricking kidding me? I should calm down? Alright, whatever u say
I get how to forward carry when the numbers equal low but what happens when your forward carry totals more than 10. Example 327,891 x 4.
3 x 4 = 12 (no need to forward carry as next one is a 2) so number is 12.....
2 x 4 = 8 (but need to forward carry as 7 next, 7 x 4 is 28....how do I carry forward 2 into the 8) do I have to jump one step back and make the original 12 a 13?
Cheers
Paul
Paul Huggett yes, the 12 turns 13
You have a couple of carries in that problem.
You make math better. Best math youtuber we can agree right?
I have a non-sever version of Dyscalculia and this has really helped me, thankyou so much!
You are making hard work of it mate, 31616 x4 = 4x3 = 12. 4x16 = 64 and the last 2 digits are 64. ans 126464. you multiply 2 numbers to avoid carries. 21613 x 5 x 2 = 10. 5 x 16 = 80. and 5 x 13 = 65 ans 108065.
Joss Cues You are right, but that's assuming you know off the top of your head that 16x4 is 64 (if you don't, you then have to pre multiple 16x4 in your head (while you are still thinking about the first part of the equation) and then get the answer to 16x4 = 64 while remembering the next part of the equation) (and you have to remember that number for the rest of the equation) and then you have to remember the next 3 equations you wrote out, this method works for EVERY SINGLE NUMBER you don't have to know anything except your basic multiplication (12x12), and the next number you are looking at.
Make the first digit of 16 greater than 3 less than 10 and you have to carry
lol no, your way is harder than his.
I've been doing it like this in my mind for years. Lol. Weird.
Same.
K463178 same
Same here. It gets harder with bigger numbers though... x * y where x and y are both larger than, say, 15 gets exponentially harder. Or rather, it requires exponentially better short-term memory for numbers. Which is exactly my problem...
same
same here and most people say its better to calculate from right to left^^
It's good when your students have a sharp memory. :(
I have a sharp memory when it comes to math and science and programming and grammar and stuff involving learning but when people ask me unimportant stuff I don't remember at all.
@@justfyox6869 i have a sharp memory when it comes to rubik's cube
You're the best! I'm currently in university and I wish they taught us this in elementary school
i never watched a video this helpful ever this is so useful i swear its the best trick i have learned since i was grade 5
I’m eleven and this has really helped me thanks for this great video!
My Australian Ant Colony same
im 7 and this helped a lot
Now you are thirteen.
I need this I failed my Math exam twiceㅠㅠㅠㅠ
"math is friend, not an annoying frustrating situation that we cry over" that was a great quote in Finding Nemo...
its not a friend. its a bully. lol no jk. its really tough though. o.o
It's been a few years since I visited this video and I've practiced a lot. I find that I'm better off if I look away from the numbers while I'm calculating, so clearly my memory has improved.
I had teachers who said it was a bad habit to do math mentally now I can show them it really works! Thanks!
that is an insane thing for teachers to say.
i was taught that being able to do it mentally is fundamental to learning it correctly.
Extremely easy! Thank you, however I'm having a hard time doing it with bigger numbers like 35 for example.
😂
Separate by the digits, multiply and connect them back
Keep in mind that it is about thinking in pairs try to see in relationships and not divisively while multiplying.
When I was younger, i'm still 11, but I did this when I started 2nd grade. My teacher would say " Young man, did you cheat?" I'd say " I dare not, if I did so i'd get abuse by my parents!".
that's adorable!
Crazy to think that you’re nearly an adult now
@@dolgid839 17?
@@yourmomm yeah
@@dolgid839 59 more days! This comment took me back thanks! :)
Thank you! You explained it in such a way that I get it. I like the way you explain not just what to do but why to do it
Cool way of looking at it. I'd add up all the numbers in my head because it was too hard for me to carry constantly, but this solves my problems. Nice.
I already knew this :) and at school my teacher was a little confuse :))
Good video, if I can suggest to leave more of a lapse time when asking viewers to try the mathematics in their head. Before you continue on with the answer!
Pause the vedio and calculate it in your head stupid
@@a.shirzad that was posted 5 years ago lol
@@pyrodemon131 you were still able to pause 5 years ago
This is vastly helpful to me in my job! Thankyou, also why do they teach us right to left math in school when this is clearly more practical?
Dude you are the best on the Tube, have a big hug from Brasil !
It's work
Thankyou
thank you so much :) I'm having my SATs soon and I'm not that good at maths so I will use this thank u so much
The guy sounds like the principal from The Inbetweeners.
***** it is
Me:goes to comments while doing the math
sees splash toons comment.
Me: goes back up and watches 😂😂😂😂
😂😂😂😂😂😂😂😂😂😂
This makes so much more sense than doing it Right to Left
After i started watching you I've been doing math in my head 24/7 tnx
why am i watching this, i should be enjoying my time on winter break,, lmao
Haha good for you doing math on break! 🤗
Math isn't boring but rather presented in a boring way in our shitty schools
I would like you to be my teacher ;-;
Skipper you will fall asleep
Skipper same
You're right ;-;
I'd be happy to be your teacher
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The way o do it is do 21 x 3. Than do 30x3 and put the total together and you have 9,063
Thank you so much, I was struggling with mental multiplication
I am relaxed now because 2.1k subscribers are having mental math problem . 😀. I am not alone ( I thought I am idiot ) in the world of numbers .
Bow down to the person who shared this solution .
THANK YOU SIR .
5:54 ILLUMINATI CONFIRMED 31616= 3(1+1)=6 and the other two numbers are 6 and 6. Therefore, 666 =o
Did you just say that 31616=6. I know this is the worst comment to logic check but I just had to
Mini Noah the Worm the two 1s in the "31616" equal two. Then you multiply that by the 3 in the "31616" and you get 6. The other two 6s put next to the third six that we got from the addition and subtraction that we recently got make 666. Therefore, SATAN
Theres always that one person
And its me...
i love u mazien hhhhh
why start with the hardest #'s first? why not start with teen #'s & work your way up to train your brain?
Rhonda Ja Idk what you mean
What about double like 2134x28?
+BuffySlaysWithIcicles “Ice-V-Buffy” so u multiply the 2 first
+BuffySlaysWithIcicles “Ice-V-Buffy” then 8
You do the same thing starting with 2 and after that, you do the same thing with 8 after, add them together.
Alex Nguyen OK thx
It's more unwieldy, but split 28 so that it becomes 2134(20+8) ---> 2134(20) + 2134(8)
Thank you so much, this isn't just mental math, I would suggest whoever is starting with this starts with doing it on paper still and than go to mental math.
Wow glad to know I'm not the only one who first learned this method until school teachers said I shouldn't keep doing this!
i just found out you can multiply a part of 2 digit from 31616
where 3*4=12
16*4=64
so 126464
What do you do if instead of a single digit to multiply by there is a double digit?
2x10 is the same as 10x2...
21*361
Separate the digits.
2|1 multiply by each and combine again.
361*20 is 7220
+361
7581
361*21=7581
How would you do 18753*24? or 18753*128?
please tell me why youd need numbers with more than 300 digists... and why would you mulitple them in your mind?
I just started practicing the Trachtenberg Method and I see people say how everything someone learned in class can be sumed up in a 5 minute video but this is true. It is so much easier and faster for me than what I learned at school. So all the years learning that specific way and this method I just found out is so much better for me, sad.
Wowwwwuuu,in my crave for knowing calculations, I came across this video in 2021. OMG, i feel so elated!!!
This is quite simple.
So this is multiplying any number by a 1 digit what about multi digit by multi digit?
Adeeb Mahmud yea your right?🤔
Ex. 3492*38 ---> 3492(30+8) --- distributive property ---> 3492(30)+3492(8). It's more unwieldy to store separate values in your head and then proceed to add them, though.
Adeeb Mahmud hi
Adeeb Mahmud ok so basically you do the exact same thing except do it however many digits over again and add zeroes to each consecutive number you come up with and then add them all in your head
He has made another video clarifying your question ;)
“3 times nothing = nothing” that nothing destroys anything!
You can't divide by nothing mate
Bro u didn’t get it, he said in the video 3 times nothing equal nothing he meant the zero, and that was a metaphor 😂😂
but who will give us that much time
Muhammad Saad
It takes almost no time if you practice.
not that hard
Where have you been all my life!!! I subscribed within the first minute of the video ✅
tysm! You taught me better than my math teacher!!
I'm in trouble.626 times 7.
6x7 = 42 , remember the 42.
7x2 = 14 , remove the 2 from remembered 42 and add a 1 from the 14 = 3.
So right now we have a 434. remember that.
Another 6x7 = ...
Oh crap, I just solved my problem -_-.. Typed for nothing..
you just need to know ur time tableles like me im 9 and i know mine till 100
karim786owais
Hey Karim, Thanks for the reply little man! It's a pretty cool thing if you know math, seems you have it going pretty well :). I'm not into math that much, It seemed pretty cool to me to learn a new may of math. Curiosity really. What I'm more interested in is that children should learn on how to write English in a way that everybody could fully understand. In a respectful way, even.
Ugh, what the heck, just don't tell me what to do kid. Typed for nothing..
I think it's better to keep track of the trailing zeros the whole way, so as not to get confused. With 626 x 7, when you multiply 6 x 7 for the first digit, you really are multiplying 600 x 7. So you drop the two zeros, multiply 6 x 7, and add the two zeros back on to the end of the number. Now you have 4,200. Then multiply the middle digit (2) x 7, which is really 20 x 7, due to the "2" being in the tens column. Drop the zero and add it back on at the end of the multiplication. 2 x 7 = 14, and add the zero back. You get 140. Add 140 to the original 4,200, by adding from left to right. 4,200 + 100 is 4,300, + 40 is 4,340. Then add the final 6 x 7: there are no zeroes to drop. You have 42. 4,340 + 40 = 4,380 + 2 = 4,382.
02:28 i auto do it that way anyway lol
what i always did
61413
x
4
__________
24 564 2
245652*
DropMJ
When I was in proper practice of mathematics I could do a lot of calculus in my head. I once solved a practical design problem mentally in around two minutes, and then spent eighteen months working out the proof, although I did do other work too at the time. The company that was employing me at the time could not understand how it took me so long to do the proof,but most of them didn't understand how I was doing it anyway. A work colleague then tried to present my work as his own, but as maths is very closely related to magic he had an accident on the way to the institute where he was going to show the proof and died. Maths is a powerful thing, and should not be confused with arithmetic.
Glad I stumbled on this. Thanks math-man!
So I have a so this mathguy is smart I have been learning on bin for 9 years
My brain hurts
MrMinevision1 hi 👋 👋
🤣🤣🤣🤣🤣
Same
I thought this was soppuse to make it easier instead triying to do this all in my head gave me a head ache
thєn juѕt prαctícє :/ єvєn thσ ítѕ 3 чєαrѕ єαrlíєr
ur not showing me how to do it mentally and what happen if we multiply by 2 digits
Very good, thank you. Left to right and pre-carryover; awesome tips!
Ty very much I was really bad at maths used to get D Everytime but I watched Maths Videos on UA-cam and got better first I learned the algorithm and carrying I got good at it then learned Cros Multiplying Now This One For Big Numbers I have learned more here then school tyvm
15 x 76? this method does not apply?
You The Divine
70*10=700
70*5=350
6*10=60
6*5=30
1140
Seems just as complicated if not more than the normal way.
its not. It's the same as reading backwards, your brain is trained in one direction; I'm not saying which method is natural, there's no "natural" method. We use latin alphabet, which is read left to right; so left to right makes "natural" sense for us (who read left to right that is). Mathematics is done with arabic numbers; and arabic is right to left... those methods were designed by people who were trained with right to left language background; the brain works with patterns and once its used to something; it becomes natural.
well other people have different methods won calculating, others have different standards, you just need to find yours.
It's more effective and faster
The system is not "very easy "
it's soooooooooo easy i'm shocked lmao no wonder people become maths geniuses
I just found your channel and I simply love you ! I love your method of teaching. Thank you
Nice explanation!