42.34% is the change from 640 to 911
Calculation steps:
[( 911 - 640 ) ÷ 640] x 100 = 42.34%
Formula
Percentage change = [(911 - 640) / 640] x 100
Subtract the new number by the original number
911 - 640 = 271
271 ÷ 640 = 0.4234375
0.4234375 x 100 = 42.34%