-19.81% is the change from 646 to 518
Calculation steps:
[( 518 - 646 ) ÷ 646] x 100 = -19.81%
Formula
Percentage change = [(518 - 646) / 646] x 100
Subtract the new number by the original number
518 - 646 = -128
-128 ÷ 646 = -0.19814241486068113
-0.19814241486068113 x 100 = -19.81%