a square number is the number you get when you multiply another number by itself. 12 is 1 x 1 = 1 so 1 is a square number 22 is 2 x 2 = 4 so 4 is a square number 32 is 3 x 3 = 9 so 9 is a square number and so on.
I hoped you understood this and use it well