-38.79% is the change from 642 to 393
Calculation steps:
[( 393 - 642 ) ÷ 642] x 100 = -38.79%
Formula
Percentage change = [(393 - 642) / 642] x 100
Subtract the new number by the original number
393 - 642 = -249
-249 ÷ 642 = -0.3878504672897196
-0.3878504672897196 x 100 = -38.79%