The side of a square is increased from 20cm to 21cm. Calculate the percentage increase in its area

A. 2.5%
B. 9.3%
C. 10.0%
D. 10.25%

Correct Answer: Option D

D. 10.25%

Explanation
old area = 20^2 = 400
new area = 21^2 = 441
% increase in area =41/400×100=10.25%