The square of the wall length was increased by 30%, by what percentage will its area increase?

Let the side of the square be equal to a, then the area of the square is c1 = a * a = a ^ 2.
1) When the side of the square is increased by 30%, then this increase can be written as follows:
a + 30% of a = a + (3/100) * a = a * (1 + 0.03) = 1.03 * a.
2) The area of the enlarged square c2 is also equal to the square of its side:
C2 = (1.03 * a) * (1.03) * a = 1.03 ^ 2 * a ^ 2 = 1.0609 * a ^ 2 ..
3) The area of the square has increased by the value: C2 – C1 = 1.0609 * a ^ 2 – a ^ 2 = a ^ 2 * (1.0609 – 1.00) = a ^ 2 * 0.0609.
4) As a percentage, this is: 0.0609 * 100% = 6.09%