Find the side of a square if its area and perimeter can be written with the same number.

A square is a rectangle with all sides equal.

Let’s denote the side of the square as a.

Then the area of the square is expressed by the formula S = a * a.

The perimeter is expressed by the formula P = 4 * a.

By condition, the perimeter is equal to the area.

Let’s write it down as an equation:

P = S.

4 * a = a * a;

4 * a – a * a = 0;

a * (4 – a) = 0.

From this equation, you can get two roots: a = 0, a = 4.

But since the side of the square must be positive, then a = 0 does not fit.

This means that only a = 4 remains.

Answer: the side of the square is 4.