-86.54% is the change from 639 to 86
Calculation steps:
[( 86 - 639 ) ÷ 639] x 100 = -86.54%
Formula
Percentage change = [(86 - 639) / 639] x 100
Subtract the new number by the original number
86 - 639 = -553
-553 ÷ 639 = -0.865414710485133
-0.865414710485133 x 100 = -86.54%