-98.5% is the change from 600 to 9
Calculation steps:
[( 9 - 600 ) ÷ 600] x 100 = -98.5%
Formula
Percentage change = [(9 - 600) / 600] x 100
Subtract the new number by the original number
9 - 600 = -591
-591 ÷ 600 = -0.985
-0.985 x 100 = -98.5%
Example