-50.78% is the change from 642 to 316
Calculation steps:
[( 316 - 642 ) ÷ 642] x 100 = -50.78%
Formula
Percentage change = [(316 - 642) / 642] x 100
Subtract the new number by the original number
316 - 642 = -326
-326 ÷ 642 = -0.5077881619937694
-0.5077881619937694 x 100 = -50.78%