-99.7% is the change from 990 to 3
Calculation steps:
[( 3 - 990 ) ÷ 990] x 100 = -99.7%
Formula
Percentage change = [(3 - 990) / 990] x 100
Subtract the new number by the original number
3 - 990 = -987
-987 ÷ 990 = -0.996969696969697
-0.996969696969697 x 100 = -99.7%
Example