30.72% is the change from 638 to 834
Calculation steps:
[( 834 - 638 ) ÷ 638] x 100 = 30.72%
Formula
Percentage change = [(834 - 638) / 638] x 100
Subtract the new number by the original number
834 - 638 = 196
196 ÷ 638 = 0.3072100313479624
0.3072100313479624 x 100 = 30.72%