26.68% is the change from 521 to 660
Calculation steps:
[( 660 - 521 ) ÷ 521] x 100 = 26.68%
Formula
Percentage change = [(660 - 521) / 521] x 100
Subtract the new number by the original number
660 - 521 = 139
139 ÷ 521 = 0.2667946257197697
0.2667946257197697 x 100 = 26.68%