-93.43% is the change from 639 to 42
Calculation steps:
[( 42 - 639 ) ÷ 639] x 100 = -93.43%
Formula
Percentage change = [(42 - 639) / 639] x 100
Subtract the new number by the original number
42 - 639 = -597
-597 ÷ 639 = -0.9342723004694836
-0.9342723004694836 x 100 = -93.43%