34.12% is the change from 639 to 857
Calculation steps:
[( 857 - 639 ) ÷ 639] x 100 = 34.12%
Formula
Percentage change = [(857 - 639) / 639] x 100
Subtract the new number by the original number
857 - 639 = 218
218 ÷ 639 = 0.3411580594679186
0.3411580594679186 x 100 = 34.12%