-37.72% is the change from 639 to 398
Calculation steps:
[( 398 - 639 ) ÷ 639] x 100 = -37.72%
Formula
Percentage change = [(398 - 639) / 639] x 100
Subtract the new number by the original number
398 - 639 = -241
-241 ÷ 639 = -0.37715179968701096
-0.37715179968701096 x 100 = -37.72%