4.85% is the change from 639 to 670
Calculation steps:
[( 670 - 639 ) ÷ 639] x 100 = 4.85%
Formula
Percentage change = [(670 - 639) / 639] x 100
Subtract the new number by the original number
670 - 639 = 31
31 ÷ 639 = 0.048513302034428794
0.048513302034428794 x 100 = 4.85%