-94.14% is the change from 256 to 15
Calculation steps:
[( 15 - 256 ) ÷ 256] x 100 = -94.14%
Formula
Percentage change = [(15 - 256) / 256] x 100
Subtract the new number by the original number
15 - 256 = -241
-241 ÷ 256 = -0.94140625
-0.94140625 x 100 = -94.14%