-8.91% is the change from 640 to 583
Calculation steps:
[( 583 - 640 ) ÷ 640] x 100 = -8.91%
Formula
Percentage change = [(583 - 640) / 640] x 100
Subtract the new number by the original number
583 - 640 = -57
-57 ÷ 640 = -0.0890625
-0.0890625 x 100 = -8.91%