-87.72% is the change from 521 to 64
Calculation steps:
[( 64 - 521 ) ÷ 521] x 100 = -87.72%
Formula
Percentage change = [(64 - 521) / 521] x 100
Subtract the new number by the original number
64 - 521 = -457
-457 ÷ 521 = -0.8771593090211133
-0.8771593090211133 x 100 = -87.72%