30.83% is the change from 639 to 836
Calculation steps:
[( 836 - 639 ) ÷ 639] x 100 = 30.83%
Formula
Percentage change = [(836 - 639) / 639] x 100
Subtract the new number by the original number
836 - 639 = 197
197 ÷ 639 = 0.3082942097026604
0.3082942097026604 x 100 = 30.83%