-82.73% is the change from 521 to 90
Calculation steps:
[( 90 - 521 ) ÷ 521] x 100 = -82.73%
Formula
Percentage change = [(90 - 521) / 521] x 100
Subtract the new number by the original number
90 - 521 = -431
-431 ÷ 521 = -0.8272552783109405
-0.8272552783109405 x 100 = -82.73%