-10% is the change from 990 to 891
Calculation steps:
[( 891 - 990 ) ÷ 990] x 100 = -10%
Formula
Percentage change = [(891 - 990) / 990] x 100
Subtract the new number by the original number
891 - 990 = -99
-99 ÷ 990 = -0.1
-0.1 x 100 = -10%
Example