36.09% is the change from 640 to 871
Calculation steps:
[( 871 - 640 ) ÷ 640] x 100 = 36.09%
Formula
Percentage change = [(871 - 640) / 640] x 100
Subtract the new number by the original number
871 - 640 = 231
231 ÷ 640 = 0.3609375
0.3609375 x 100 = 36.09%