-36% is the change from 400 to 256
Calculation steps:
[( 256 - 400 ) ÷ 400] x 100 = -36%
Formula
Percentage change = [(256 - 400) / 400] x 100
Subtract the new number by the original number
256 - 400 = -144
-144 ÷ 400 = -0.36
-0.36 x 100 = -36%
Example