30.52% is the change from 639 to 834
Calculation steps:
[( 834 - 639 ) ÷ 639] x 100 = 30.52%
Formula
Percentage change = [(834 - 639) / 639] x 100
Subtract the new number by the original number
834 - 639 = 195
195 ÷ 639 = 0.3051643192488263
0.3051643192488263 x 100 = 30.52%