If the length of each side of a square is increased by 25%, by what percentage does its area increase?

Explanation

When the side of a square is increased by 25%, the new side length becomes 1.25 times the original. The new area is (1.25)^2 = 1.5625 times the original area, which means the area increases by (1.5625 - 1) × 100% = 56.25%.