-47.81% is the change from 640 to 334
Calculation steps:
[( 334 - 640 ) ÷ 640] x 100 = -47.81%
Formula
Percentage change = [(334 - 640) / 640] x 100
Subtract the new number by the original number
334 - 640 = -306
-306 ÷ 640 = -0.478125
-0.478125 x 100 = -47.81%