-50% is the change from 644 to 322
Calculation steps:
[( 322 - 644 ) ÷ 644] x 100 = -50%
Formula
Percentage change = [(322 - 644) / 644] x 100
Subtract the new number by the original number
322 - 644 = -322
-322 ÷ 644 = -0.5
-0.5 x 100 = -50%
Example