30% is the change from 40 to 52
Calculation steps:
[( 52 - 40 ) ÷ 40] x 100 = 30%
Formula
Percentage change = [(52 - 40) / 40] x 100
Subtract the new number by the original number
52 - 40 = 12
12 ÷ 40 = 0.3
0.3 x 100 = 30%
Example