-50.23% is the change from 643 to 320
Calculation steps:
[( 320 - 643 ) ÷ 643] x 100 = -50.23%
Formula
Percentage change = [(320 - 643) / 643] x 100
Subtract the new number by the original number
320 - 643 = -323
-323 ÷ 643 = -0.5023328149300156
-0.5023328149300156 x 100 = -50.23%