-39.35% is the change from 643 to 390
Calculation steps:
[( 390 - 643 ) ÷ 643] x 100 = -39.35%
Formula
Percentage change = [(390 - 643) / 643] x 100
Subtract the new number by the original number
390 - 643 = -253
-253 ÷ 643 = -0.39346811819595645
-0.39346811819595645 x 100 = -39.35%