-87.88% is the change from 817 to 99
Calculation steps:
[( 99 - 817 ) ÷ 817] x 100 = -87.88%
Formula
Percentage change = [(99 - 817) / 817] x 100
Subtract the new number by the original number
99 - 817 = -718
-718 ÷ 817 = -0.8788249694002448
-0.8788249694002448 x 100 = -87.88%