15% is the change from 540 to 621
Calculation steps:
[( 621 - 540 ) ÷ 540] x 100 = 15%
Formula
Percentage change = [(621 - 540) / 540] x 100
Subtract the new number by the original number
621 - 540 = 81
81 ÷ 540 = 0.15
0.15 x 100 = 15%
Example