-49.61% is the change from 256 to 129
Calculation steps:
[( 129 - 256 ) ÷ 256] x 100 = -49.61%
Formula
Percentage change = [(129 - 256) / 256] x 100
Subtract the new number by the original number
129 - 256 = -127
-127 ÷ 256 = -0.49609375
-0.49609375 x 100 = -49.61%