-38.08% is the change from 646 to 400
Calculation steps:
[( 400 - 646 ) ÷ 646] x 100 = -38.08%
Formula
Percentage change = [(400 - 646) / 646] x 100
Subtract the new number by the original number
400 - 646 = -246
-246 ÷ 646 = -0.38080495356037153
-0.38080495356037153 x 100 = -38.08%