56.43% is the change from 521 to 815
Calculation steps:
[( 815 - 521 ) ÷ 521] x 100 = 56.43%
Formula
Percentage change = [(815 - 521) / 521] x 100
Subtract the new number by the original number
815 - 521 = 294
294 ÷ 521 = 0.564299424184261
0.564299424184261 x 100 = 56.43%