31.03% is the change from 638 to 836
Calculation steps:
[( 836 - 638 ) ÷ 638] x 100 = 31.03%
Formula
Percentage change = [(836 - 638) / 638] x 100
Subtract the new number by the original number
836 - 638 = 198
198 ÷ 638 = 0.3103448275862069
0.3103448275862069 x 100 = 31.03%