-87.33% is the change from 521 to 66
Calculation steps:
[( 66 - 521 ) ÷ 521] x 100 = -87.33%
Formula
Percentage change = [(66 - 521) / 521] x 100
Subtract the new number by the original number
66 - 521 = -455
-455 ÷ 521 = -0.8733205374280231
-0.8733205374280231 x 100 = -87.33%