-39.63% is the change from 646 to 390
Calculation steps:
[( 390 - 646 ) ÷ 646] x 100 = -39.63%
Formula
Percentage change = [(390 - 646) / 646] x 100
Subtract the new number by the original number
390 - 646 = -256
-256 ÷ 646 = -0.39628482972136225
-0.39628482972136225 x 100 = -39.63%