-83.1% is the change from 639 to 108
Calculation steps:
[( 108 - 639 ) ÷ 639] x 100 = -83.1%
Formula
Percentage change = [(108 - 639) / 639] x 100
Subtract the new number by the original number
108 - 639 = -531
-531 ÷ 639 = -0.8309859154929577
-0.8309859154929577 x 100 = -83.1%