-99% is the change from 200 to 2
Calculation steps:
[( 2 - 200 ) ÷ 200] x 100 = -99%
Formula
Percentage change = [(2 - 200) / 200] x 100
Subtract the new number by the original number
2 - 200 = -198
-198 ÷ 200 = -0.99
-0.99 x 100 = -99%
Example