-39.19% is the change from 643 to 391
Calculation steps:
[( 391 - 643 ) ÷ 643] x 100 = -39.19%
Formula
Percentage change = [(391 - 643) / 643] x 100
Subtract the new number by the original number
391 - 643 = -252
-252 ÷ 643 = -0.39191290824261277
-0.39191290824261277 x 100 = -39.19%