49.53% is the change from 640 to 957
Calculation steps:
[( 957 - 640 ) ÷ 640] x 100 = 49.53%
Formula
Percentage change = [(957 - 640) / 640] x 100
Subtract the new number by the original number
957 - 640 = 317
317 ÷ 640 = 0.4953125
0.4953125 x 100 = 49.53%