-77.19% is the change from 640 to 146
Calculation steps:
[( 146 - 640 ) ÷ 640] x 100 = -77.19%
Formula
Percentage change = [(146 - 640) / 640] x 100
Subtract the new number by the original number
146 - 640 = -494
-494 ÷ 640 = -0.771875
-0.771875 x 100 = -77.19%