-87.24% is the change from 635 to 81
Calculation steps:
[( 81 - 635 ) ÷ 635] x 100 = -87.24%
Formula
Percentage change = [(81 - 635) / 635] x 100
Subtract the new number by the original number
81 - 635 = -554
-554 ÷ 635 = -0.8724409448818897
-0.8724409448818897 x 100 = -87.24%