Use either of the shortcuts. For √(ABCD +1), where A, B, C, and D are positive consecutive integers, we have AD + 1 or BC - 1. So 17 x 20 + 1 = 341 and 18 x 19 - 1 = 341. FUN FACT: Any four positive consecutive integers multipled plus one is a perfect square. For example, 2 x 3 x 4 x 5 + 1 = 121. 11^2 = 121. Try it with your own example.
Use either of the shortcuts. For √(ABCD +1), where A, B, C, and D are positive consecutive integers, we have AD + 1 or BC - 1. So 17 x 20 + 1 = 341 and 18 x 19 - 1 = 341.
FUN FACT: Any four positive consecutive integers multipled plus one is a perfect square. For example, 2 x 3 x 4 x 5 + 1 = 121. 11^2 = 121.
Try it with your own example.