-75% is the change from 256 to 64
Calculation steps:
[( 64 - 256 ) ÷ 256] x 100 = -75%
Formula
Percentage change = [(64 - 256) / 256] x 100
Subtract the new number by the original number
64 - 256 = -192
-192 ÷ 256 = -0.75
-0.75 x 100 = -75%
Example