-49.69% is the change from 642 to 323
Calculation steps:
[( 323 - 642 ) ÷ 642] x 100 = -49.69%
Formula
Percentage change = [(323 - 642) / 642] x 100
Subtract the new number by the original number
323 - 642 = -319
-319 ÷ 642 = -0.4968847352024922
-0.4968847352024922 x 100 = -49.69%