-19.75% is the change from 638 to 512
Calculation steps:
[( 512 - 638 ) ÷ 638] x 100 = -19.75%
Formula
Percentage change = [(512 - 638) / 638] x 100
Subtract the new number by the original number
512 - 638 = -126
-126 ÷ 638 = -0.1974921630094044
-0.1974921630094044 x 100 = -19.75%