-88.91% is the change from 640 to 71
Calculation steps:
[( 71 - 640 ) ÷ 640] x 100 = -88.91%
Formula
Percentage change = [(71 - 640) / 640] x 100
Subtract the new number by the original number
71 - 640 = -569
-569 ÷ 640 = -0.8890625
-0.8890625 x 100 = -88.91%