-39.66% is the change from 643 to 388
Calculation steps:
[( 388 - 643 ) ÷ 643] x 100 = -39.66%
Formula
Percentage change = [(388 - 643) / 643] x 100
Subtract the new number by the original number
388 - 643 = -255
-255 ÷ 643 = -0.3965785381026439
-0.3965785381026439 x 100 = -39.66%