-50.39% is the change from 256 to 127
Calculation steps:
[( 127 - 256 ) ÷ 256] x 100 = -50.39%
Formula
Percentage change = [(127 - 256) / 256] x 100
Subtract the new number by the original number
127 - 256 = -129
-129 ÷ 256 = -0.50390625
-0.50390625 x 100 = -50.39%