-61.79% is the change from 670 to 256
Calculation steps:
[( 256 - 670 ) ÷ 670] x 100 = -61.79%
Formula
Percentage change = [(256 - 670) / 670] x 100
Subtract the new number by the original number
256 - 670 = -414
-414 ÷ 670 = -0.6179104477611941
-0.6179104477611941 x 100 = -61.79%