What are not square numbers?

Not square numbers are integers that cannot be expressed as the square of an integer. For example, numbers like 2, 3, 5, 6, and 7 are not square numbers, as there are no integers whose square equals these values. In contrast, square numbers include values like 0, 1, 4, 9, and 16, which correspond to the squares of integers 0, 1, 2, 3, and 4, respectively.