-49.8% is the change from 510 to 256
Calculation steps:
[( 256 - 510 ) ÷ 510] x 100 = -49.8%
Formula
Percentage change = [(256 - 510) / 510] x 100
Subtract the new number by the original number
256 - 510 = -254
-254 ÷ 510 = -0.4980392156862745
-0.4980392156862745 x 100 = -49.8%