31.29% is the change from 521 to 684
Calculation steps:
[( 684 - 521 ) ÷ 521] x 100 = 31.29%
Formula
Percentage change = [(684 - 521) / 521] x 100
Subtract the new number by the original number
684 - 521 = 163
163 ÷ 521 = 0.31285988483685223
0.31285988483685223 x 100 = 31.29%