By what percentage will the area of a square increase if its side increases by 10%? (with explanation)

21%

Step-by-step explanation:

side of square = a

area of square = a²

increased side = a+10% = a*1.1 = 1.1a

increased area = (1.1a) ² = 1.21a²

the difference is 0.21 which is = 21%