4.84% is the change from 640 to 671
Calculation steps:
[( 671 - 640 ) ÷ 640] x 100 = 4.84%
Formula
Percentage change = [(671 - 640) / 640] x 100
Subtract the new number by the original number
671 - 640 = 31
31 ÷ 640 = 0.0484375
0.0484375 x 100 = 4.84%