-90.99% is the change from 999 to 90
Calculation steps:
[( 90 - 999 ) ÷ 999] x 100 = -90.99%
Formula
Percentage change = [(90 - 999) / 999] x 100
Subtract the new number by the original number
90 - 999 = -909
-909 ÷ 999 = -0.9099099099099099
-0.9099099099099099 x 100 = -90.99%