2.56% is the change from 624 to 640
Calculation steps:
[( 640 - 624 ) ÷ 624] x 100 = 2.56%
Formula
Percentage change = [(640 - 624) / 624] x 100
Subtract the new number by the original number
640 - 624 = 16
16 ÷ 624 = 0.02564102564102564
0.02564102564102564 x 100 = 2.56%