A complete square number is a number that can be written as the square of a positive integer. For example, 36 is 6×6 and 49 is 7×7.
The sum of n odd numbers starting from 1 is a complete square number, that is,1+3+5+7+…+(2n-1) = n 2;
The last bit of each complete square number is one of 0, 1, 4, 5 and 6;
Every complete square number is either divisible by 3, or negative 1 is divisible by 3;
Every complete square number can be divisible by 4 or by 1.
Every complete square number can be divisible by 5 at last, or can be divisible by 5 by adding 1 or subtracting 1. ...