-15.81% is the change from 639 to 538
Calculation steps:
[( 538 - 639 ) ÷ 639] x 100 = -15.81%
Formula
Percentage change = [(538 - 639) / 639] x 100
Subtract the new number by the original number
538 - 639 = -101
-101 ÷ 639 = -0.15805946791862285
-0.15805946791862285 x 100 = -15.81%