-94.68% is the change from 639 to 34
Calculation steps:
[( 34 - 639 ) ÷ 639] x 100 = -94.68%
Formula
Percentage change = [(34 - 639) / 639] x 100
Subtract the new number by the original number
34 - 639 = -605
-605 ÷ 639 = -0.94679186228482
-0.94679186228482 x 100 = -94.68%