-81.67% is the change from 491 to 90
Calculation steps:
[( 90 - 491 ) ÷ 491] x 100 = -81.67%
Formula
Percentage change = [(90 - 491) / 491] x 100
Subtract the new number by the original number
90 - 491 = -401
-401 ÷ 491 = -0.8167006109979633
-0.8167006109979633 x 100 = -81.67%