-51.02% is the change from 639 to 313
Calculation steps:
[( 313 - 639 ) ÷ 639] x 100 = -51.02%
Formula
Percentage change = [(313 - 639) / 639] x 100
Subtract the new number by the original number
313 - 639 = -326
-326 ÷ 639 = -0.5101721439749609
-0.5101721439749609 x 100 = -51.02%