-40.39% is the change from 671 to 400
Calculation steps:
[( 400 - 671 ) ÷ 671] x 100 = -40.39%
Formula
Percentage change = [(400 - 671) / 671] x 100
Subtract the new number by the original number
400 - 671 = -271
-271 ÷ 671 = -0.4038748137108793
-0.4038748137108793 x 100 = -40.39%