-91.39% is the change from 639 to 55
Calculation steps:
[( 55 - 639 ) ÷ 639] x 100 = -91.39%
Formula
Percentage change = [(55 - 639) / 639] x 100
Subtract the new number by the original number
55 - 639 = -584
-584 ÷ 639 = -0.9139280125195618
-0.9139280125195618 x 100 = -91.39%