-99% is the change from 899 to 9
Calculation steps:
[( 9 - 899 ) ÷ 899] x 100 = -99%
Formula
Percentage change = [(9 - 899) / 899] x 100
Subtract the new number by the original number
9 - 899 = -890
-890 ÷ 899 = -0.9899888765294772
-0.9899888765294772 x 100 = -99%