-50.39% is the change from 512 to 254
Calculation steps:
[( 254 - 512 ) ÷ 512] x 100 = -50.39%
Formula
Percentage change = [(254 - 512) / 512] x 100
Subtract the new number by the original number
254 - 512 = -258
-258 ÷ 512 = -0.50390625
-0.50390625 x 100 = -50.39%