-99.7% is the change from 999 to 3
Calculation steps:
[( 3 - 999 ) ÷ 999] x 100 = -99.7%
Formula
Percentage change = [(3 - 999) / 999] x 100
Subtract the new number by the original number
3 - 999 = -996
-996 ÷ 999 = -0.996996996996997
-0.996996996996997 x 100 = -99.7%