-39.19% is the change from 421 to 256
Calculation steps:
[( 256 - 421 ) ÷ 421] x 100 = -39.19%
Formula
Percentage change = [(256 - 421) / 421] x 100
Subtract the new number by the original number
256 - 421 = -165
-165 ÷ 421 = -0.3919239904988123
-0.3919239904988123 x 100 = -39.19%