65% is the change from 40 to 66
Calculation steps:
[( 66 - 40 ) ÷ 40] x 100 = 65%
Formula
Percentage change = [(66 - 40) / 40] x 100
Subtract the new number by the original number
66 - 40 = 26
26 ÷ 40 = 0.65
0.65 x 100 = 65%
Example