Question

How do I demonstrate that the digits of a perfect square cannot add up to 2,3,5,6,or8?

Answer 1

2^2=4
3^2=9
4^2=16 (1+6=7)
5^2=25 (2+5=7)
6^2=36 (3+6=9)
7^2=49 (4+9=13)
and so on and so forth.