31850% is the change from 2 to 639
Calculation steps:
[( 639 - 2 ) ÷ 2] x 100 = 31850%
Formula
Percentage change = [(639 - 2) / 2] x 100
Subtract the new number by the original number
639 - 2 = 637
637 ÷ 2 = 318.5
318.5 x 100 = 31850%
Example