-17.42% is the change from 310 to 256
Calculation steps:
[( 256 - 310 ) ÷ 310] x 100 = -17.42%
Formula
Percentage change = [(256 - 310) / 310] x 100
Subtract the new number by the original number
256 - 310 = -54
-54 ÷ 310 = -0.17419354838709677
-0.17419354838709677 x 100 = -17.42%