39.55% is the change from 660 to 921
Calculation steps:
[( 921 - 660 ) ÷ 660] x 100 = 39.55%
Formula
Percentage change = [(921 - 660) / 660] x 100
Subtract the new number by the original number
921 - 660 = 261
261 ÷ 660 = 0.39545454545454545
0.39545454545454545 x 100 = 39.55%