-80.59% is the change from 639 to 124
Calculation steps:
[( 124 - 639 ) ÷ 639] x 100 = -80.59%
Formula
Percentage change = [(124 - 639) / 639] x 100
Subtract the new number by the original number
124 - 639 = -515
-515 ÷ 639 = -0.8059467918622848
-0.8059467918622848 x 100 = -80.59%