-50.54% is the change from 645 to 319
Calculation steps:
[( 319 - 645 ) ÷ 645] x 100 = -50.54%
Formula
Percentage change = [(319 - 645) / 645] x 100
Subtract the new number by the original number
319 - 645 = -326
-326 ÷ 645 = -0.5054263565891473
-0.5054263565891473 x 100 = -50.54%