5% is the change from 40 to 42
Calculation steps:
[( 42 - 40 ) ÷ 40] x 100 = 5%
Formula
Percentage change = [(42 - 40) / 40] x 100
Subtract the new number by the original number
42 - 40 = 2
2 ÷ 40 = 0.05
0.05 x 100 = 5%
Example