Mental Multiplication Math Trick - Multiply numbers in your head near 100
Вставка
- Опубліковано 21 лют 2013
- This mental multiplication math trick uses the idea of a third number - a base number - to help us multiply two numbers in your head. This series of videos first looks at multiplying numbers near 10 using base 10. The second video looks at multiplying using base 20 and 30. The third video looks at how to apply this mental multiplication trick to numbers near 50. The forth video the investigates ho to easilt mentally multiply numbers near to 100. Continue your mental math multiplication abilties here!
To donate to the tecmath channel:paypal.me/tecmath
To support tecmath on Patreon: / tecmath
To buy tecmath mechandise: teespring.com/stores/tecmath-...
![Lp. Последняя Реальность #107 РОДНОЙ ДОМ [Финал] • Майнкрафт](http://i.ytimg.com/vi/IK3QKzKUlHM/mqdefault.jpg)
I’ve been watching all your video series on multiplication and they really helped a lot in improving my multiplication skills! You’re the best math teacher I never had! Thanks so much for these videos..God bless!
Just starting from no 1 and working my way up.... Thanks tecmath enjoying maths again..
For those that know algebra, this is basically changing it to multiplying two binomials and using the FOIL method.
105x107
Change that to
(100+5)x(100+7)
The cross-adding is combining the FOI in the FOIL method. It makes it easy because your First numbers are 100.
10000
+ 700
+ 500
----
11200
So now it’s just the Last number added to that, or
5x7 = 35
11235 is the answer.
Not sure the foil method is easier to do in your head or not. You want to have fewer numbers to hold in sort term memory from mental math. But it's whatever works best for you.
Thank you. Amazing tricks.
Dude thanks for the math cause I'm getting those equations next week and this one
Thanks for this series, very good teaching :D
Thanks a lot, great!
I really love all these - thanks!
McGavel1 stupid
@@lorraineday8150 ?
very amazing thanks very much indeed,
Great video
I learnt a great concept today May 22, 2017 (IST)
i love so much your math trick..!! :P
very good teacher
very good,
This really helps me in math kind of hated math.
Doing the math, this will also work with fractions or decimals as long as you do the multiplication correctly.
Also, I like how this is recursive
Say I wanted to do 120 × 123
Base 100:
+21, +23
14300 + 21 × 23
Base 20:
+1, +3
24 × 20 = 480 + 3 = 483
So 121 × 123 is 14300 + 483 = 14783
----
Also possible with 120 as a base, but that is harder for me to do in my head
best method 👍
I LOVE UR VIDS ;]
i like this makes it so much faster atleast if your dealing with factors of 10 ....10, 100, 1000, 10000, and so on so if its 40,010 x 40,020 you would just add 200 to what ever you get by timing 400,300,000 by 4 ....which is 1,601,200,200...so much faster this way than doing it the typical way
Now, supposing we'd chosen the use the -4/5 difference. It still works, but it's a more difficult choice to do mentally.
So, 24 -4/5 = 23 1/5 = 23.2
Since we diminished this difference, we have to multiple by the secondary base of 100: 23.2 x 100 = 2320
Now the rest is the same: +4 x -4 = -16. So, 2320 -16 = 2304
I like your multiplication and l hope l will win in the math challenge
What about when you have mixed base like one number base 10 and another base 100?
Use the "two base" method, where the secondary base is a simple multiple of the main base.
For example, use: 20 (main) & 100 (main x5), to multiply 24 by 96
So, the differences become: 24 - 20 = +4 96 - 100 = -4
Now the important bit: Before cross adding, multiply (or divide) one by that base factor, 5. Either: +4 x 5 = +20 or -4 / 5 = -4/5
Using the easier +20 gives: 96 +20 = 116 x 20 (main) = 2320
Now multiply the (unmodified) differences: +4 x -4 = -16
And finish it: 2320 -16 = 2304
109×102=11100
@@SurajPal-kx5tr +18
I see, so confusing i dont get it at all
(I suck at eng.)
thanks
to awesome!!!!!!!
sure.
Better than the other way round I think.
Great video. But I wish
he would line up, right justify, his digits when doing addition & subtraction
it's fun 👏👏
i got all the answers correct
can u line the numbers proply thats what i didnt understand
With 61x50, why not do 61x5x10 instead of x100/2?
Hi I’ve been learning this from your videos I learnt base of 10 an 20 ect then I tried showing my partner, I had done it with numbers like 23 x 28 etc using a base of 20 an ect then she said try 86x 86 an using the formula I couldn’t work it out it didn’t seem to work out the same way an I looked through your vids an couldn’t find you using the same numbers for this does it work out an could you show it doing so ? Thanks
Hey what about 640×311
Do i need base 310 or something
😑😏😏
Can I request a video you can try to do?
C+=Dramp=cClamp
O+B
C=cSourceryU=cvlamp
n.d
very cool.
What happen when you have 537*312 ?
How to slove 243 multiply 823and 127&485
_’Aigt “_ = 8
you rock .........i used to hate maths [like poop]
but you saved me [If i become a pilot I would like to thank you ]
Abhigyan Chandra that's a scary content right there
Excuses me, l don't understand how you do the 11100?
What about if under say 123× 56
Any trick for number far apart of each other and closeto two different bases.
eg. 23x78
Base 20 (I find it easier to pick the base that is close to the lowest number):
+3 & +58
78+3 = 81 * 2 = 162*10 = 1620
3*58 = (150+24) = 174
1620 + 174 = 1794.
Could use a base closest to the center of the two
Eg:
23 × 78 :base 50
-27, 28
51 × 50 = 5100 ÷ 2 = 2550
-27 × 28 :base 30 negative of 27×28
-3, -2
25 × 20 = 500
500 + 6 = 506
23 × 78 = 2550 - 506 = 2044
Another way you could do it is say "oh, thats the same as 46 × 39", and use base 40, which would be less work
I think all bases r appropriate
13×83, we can use all bases from 10 to 80, it work every base is appropriate for it
you crazy I already now my time tables
What bro tell me
what about 100?
108*56=? Same question of "Chetan singh", and 139*144=?
Thanks for your videos!
dont always use the same trick, some maths questions will require different tricks, strategies etc
do 100x56. then just add 8 x 56. just as simple as the method above
139 × 144: Base 100
+39, +44
139 + 44 = 144 + 39 = 183
183 × 100 = 18300
So 139 × 144 is 18300 + 39 × 44
Do the trick again to figure out 39 × 44, with a base of 40, then add that final result to 18300, and you have your answer.
@@Nerketur This does work, however, how would you keep track of this in your head?
What about 51x13
With this, just 510 + 153
There is a reasonable conclusion on this topic in this channel ua-cam.com/video/T8lrOXlNJQQ/v-deo.html
It seems to be most of the numbers he uses add up to ten. tried to do 42x45. His was, It didn't work. The answer from his formula came to 2014. But when i used the calculator the answer was 1890. So where am i going wrong. Or it his formula right.
use the bases of 50
He's right...you're making a mistake somewhere...use a base close to your equations numbers to simplify.
42x45. Use base 40 add 2+5 =7 (when both are above the base just add the 'ones' column together for the final digit) and 2 x 5=10 | 42+5=47 or 45+2=47 so 47 x 40 (or 470 x 4)=1880 + 10 = 1890
Base 50 is 42 (-8)x 45 (-5) , number become 37. 37x50 (or 370x5)= 3700/2 = 1850. Then (-8 x -5) = 40...1850+40=1890. Same answer no matter what base you use.
check your multiplication
-8 x -5 =40.....2 negatives equal positive 40
42 -5=37 x 100=3700/2=1850+40=1890
hope this helps
103×93 ka trick solution kare
This method becomes impossible to do in your head once you get to the 150's and higher, or numbers too far apart from each other.
Yeah no it’s after 110 sadly 111 multiplied by 115 ain’t 11605
@@siguythetacoguy7438 Actually those two numbers work. The answer I got using the method was 12,765, so it works.
Sir you are vidious really helpful but some problem do not solve for example 49 multiply 87 and you told 55 multiply 56 solve 3050.... Tell me and 13 multiply 69 give to vidious
49 × 87: base 60
- 11, +27
87 - 11 = 76
76 × 60 = 4560
-11 × 27 = -297
49 × 87 = 4560 - 297 = 4263
We are use vedic math
The first answer is the Fibonacci sequence
(x+a)(x+b)
Plz explain this 107*79
I'm late but here you go.
Base 70.
107+9 or 79+37 = 116
1160x7= 8120 and 9x37=333
8120+333=8453
What about 125x15
benito villarente 1975
benito villarente Multiply by 20 then add half of that
5th
Wat Isabella plus Lucy
The same age as the other SIDE is your birthday
How 97 Tim's 36 ?
I'm late but here you go. Base 30
.
97=67 more and 36=6 more. so 97 + 6 or 36 + 67 =103
.
10,30 x 3 =3090 and 67 x 6 =402
.
3090 + 402= *3492*
105 x 107 = 10700 + 535 = 11235
Savan kumar answer is 105×107=11200
21 x 14 = 280 + 14 = 294
108*56=?????
I used the bases of 50 which was the video before this one.
58 6
108 X 56
108+6= 114
114 x 100=11,400
11,400/2= 5700
---------
58 x 6 = (I seriously had to break this down)=
6 X 5 = 30 but of course were doing 50 X 6 = 300
then 8 x 6= 48
300+ 48= 348
then we add both together: 5,700 + 348 = 6,048
Thus, 108 x 56 = 6,048.
Josue... very good... I'd have done the same. It certainly gets much more complicated the larger the difference between the two numbers being multiplied. It is easy if you follow the rule using paper but I'd have got way lost trying to do this calc in my head, which is the principle of this technique. I'd get there but it would be very frustrating.
Or you could do it the easy way (100x56)+(8x50)+(8x6)=6048.This equates to 5600+400+48. It's good to know more than one way to solve problems. Always use the easiest way. Work smart not hard. I didn't use any base except common sense.
chetan singh near 100
@Led Zep: problem with that is (I'm not saying it doesn't work) it's too hard to hold all those number in your head. The methods this guy presents minimizes the number you have to try to store in your head. On paper, your method is great. But unless you have a really good memory, it's too many numbers floating in your head. That's always the challenge for me--remembering the sub-calculations. The actual computation is usually pretty simple.
105 x 101 = 10500 + 105 = 10605
104 x 97 = 10400 - 312 = 10088
95
10400-312. 104x100 less 104x3.
109 x 102 = 10900 + 218 = 11118
second :D
U r saying so slowly
this is confusing
parsa kimiaie not really. Maybe you world view the base 10 videos and work your way up. It's ACTUALLY very useful and easy....period is not only me...scroll the comments. ....it's not a freebie...you have to learn it and practice but once you get out in your head you'll easily be doing this in your head with correct answers while others screw up on paper
First
How I ended up here from cat videos?
Mrbargais shut up
this is the worst video by him as it is 5 years gone but he has only 129,788 views and only 890 likes vs 47 dislikes.
BTW I love ur videos very much :D
I have a different way, this is cheating.
But my way may be ineffecient, as it took me 20 minutes of staring at a wall to solve 355 * 268.
There is no way to "cheat at math". In fact Arthur Benjamin, famous mathematician, one said that math simply is finding formulas and applying it to different numbers (by the way I very much paraphrased there please see his lecture at Ted X Oxford for the exact words.
How is this "cheating" you are still calculating answers manually. Man I hope you're some dumb kid and not a member of society with a divers license or a job that matters to anyone
MMJ Gaming yeah he’s my idol I learn some tricks from him ! I learnt the golden ratio from him too
Dude this guy plays free online games and has no life then says this is cheating
2020 anyone
So darn long hurry up already.
Very bad chanel
Give a like to my comment if you agree
C+=Dramp=cClamp
O+B
C=cSourceryU=cvlamp
n.d
C+=Dramp=cClamp
O+B
C=cSourceryU=cvlamp
n.d