-87.69% is the change from 999 to 123
Calculation steps:
[( 123 - 999 ) ÷ 999] x 100 = -87.69%
Formula
Percentage change = [(123 - 999) / 999] x 100
Subtract the new number by the original number
123 - 999 = -876
-876 ÷ 999 = -0.8768768768768769
-0.8768768768768769 x 100 = -87.69%