-79.94% is the change from 638 to 128
Calculation steps:
[( 128 - 638 ) ÷ 638] x 100 = -79.94%
Formula
Percentage change = [(128 - 638) / 638] x 100
Subtract the new number by the original number
128 - 638 = -510
-510 ÷ 638 = -0.799373040752351
-0.799373040752351 x 100 = -79.94%