30.99% is the change from 639 to 837
Calculation steps:
[( 837 - 639 ) ÷ 639] x 100 = 30.99%
Formula
Percentage change = [(837 - 639) / 639] x 100
Subtract the new number by the original number
837 - 639 = 198
198 ÷ 639 = 0.30985915492957744
0.30985915492957744 x 100 = 30.99%