6.58% is the change from 638 to 680
Calculation steps:
[( 680 - 638 ) ÷ 638] x 100 = 6.58%
Formula
Percentage change = [(680 - 638) / 638] x 100
Subtract the new number by the original number
680 - 638 = 42
42 ÷ 638 = 0.06583072100313479
0.06583072100313479 x 100 = 6.58%