28.21% is the change from 521 to 668
Calculation steps:
[( 668 - 521 ) ÷ 521] x 100 = 28.21%
Formula
Percentage change = [(668 - 521) / 521] x 100
Subtract the new number by the original number
668 - 521 = 147
147 ÷ 521 = 0.2821497120921305
0.2821497120921305 x 100 = 28.21%