-98.92% is the change from 830 to 9
Calculation steps:
[( 9 - 830 ) ÷ 830] x 100 = -98.92%
Formula
Percentage change = [(9 - 830) / 830] x 100
Subtract the new number by the original number
9 - 830 = -821
-821 ÷ 830 = -0.9891566265060241
-0.9891566265060241 x 100 = -98.92%