-17.95% is the change from 312 to 256
Calculation steps:
[( 256 - 312 ) ÷ 312] x 100 = -17.95%
Formula
Percentage change = [(256 - 312) / 312] x 100
Subtract the new number by the original number
256 - 312 = -56
-56 ÷ 312 = -0.1794871794871795
-0.1794871794871795 x 100 = -17.95%