The Square Root Trick

By Joshua

I thought this trick up all by myself. It's one about square roots (hence the name) and here's how it works:
If the sum of two square roots equals 10 or a multiple of 10 then the square of both numbers will have the same number in the ones place. For example:
*9 and 1. Added together the sum is 10. Square each number and you get 81 and 1. The number in the ones place of both answers is 1.
*4 and 6 together make 10. Their squares are 16 and 36. The number in the ones place is 6 for both.
*12 and 8 together make 20. Their squares are 144 and 64. The number in the ones place of both is 4.