-24.71% is the change from 340 to 256
Calculation steps:
[( 256 - 340 ) ÷ 340] x 100 = -24.71%
Formula
Percentage change = [(256 - 340) / 340] x 100
Subtract the new number by the original number
256 - 340 = -84
-84 ÷ 340 = -0.24705882352941178
-0.24705882352941178 x 100 = -24.71%