-4.22% is the change from 640 to 613
Calculation steps:
[( 613 - 640 ) ÷ 640] x 100 = -4.22%
Formula
Percentage change = [(613 - 640) / 640] x 100
Subtract the new number by the original number
613 - 640 = -27
-27 ÷ 640 = -0.0421875
-0.0421875 x 100 = -4.22%