Square Days occur when your day age is a square number.

A square number is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 9 is a square number, since it can be written as 3 x 3.

1² = 1

2² = 4

3² = 9

4² = 16

5² = 25

Square numbers can be determined by the formula: