-50.39% is the change from 643 to 319
Calculation steps:
[( 319 - 643 ) ÷ 643] x 100 = -50.39%
Formula
Percentage change = [(319 - 643) / 643] x 100
Subtract the new number by the original number
319 - 643 = -324
-324 ÷ 643 = -0.5038880248833593
-0.5038880248833593 x 100 = -50.39%