-99% is the change from 1000 to 10
Calculation steps:
[( 10 - 1000 ) ÷ 1000] x 100 = -99%
Formula
Percentage change = [(10 - 1000) / 1000] x 100
Subtract the new number by the original number
10 - 1000 = -990
-990 ÷ 1000 = -0.99
-0.99 x 100 = -99%
Example