-37.85% is the change from 642 to 399
Calculation steps:
[( 399 - 642 ) ÷ 642] x 100 = -37.85%
Formula
Percentage change = [(399 - 642) / 642] x 100
Subtract the new number by the original number
399 - 642 = -243
-243 ÷ 642 = -0.37850467289719625
-0.37850467289719625 x 100 = -37.85%