31800% is the change from 2 to 638
Calculation steps:
[( 638 - 2 ) ÷ 2] x 100 = 31800%
Formula
Percentage change = [(638 - 2) / 2] x 100
Subtract the new number by the original number
638 - 2 = 636
636 ÷ 2 = 318
318 x 100 = 31800%
Example