-80.08% is the change from 256 to 51
Calculation steps:
[( 51 - 256 ) ÷ 256] x 100 = -80.08%
Formula
Percentage change = [(51 - 256) / 256] x 100
Subtract the new number by the original number
51 - 256 = -205
-205 ÷ 256 = -0.80078125
-0.80078125 x 100 = -80.08%