-99.53% is the change from 640 to 3
Calculation steps:
[( 3 - 640 ) ÷ 640] x 100 = -99.53%
Formula
Percentage change = [(3 - 640) / 640] x 100
Subtract the new number by the original number
3 - 640 = -637
-637 ÷ 640 = -0.9953125
-0.9953125 x 100 = -99.53%