-79.52% is the change from 830 to 170
Calculation steps:
[( 170 - 830 ) ÷ 830] x 100 = -79.52%
Formula
Percentage change = [(170 - 830) / 830] x 100
Subtract the new number by the original number
170 - 830 = -660
-660 ÷ 830 = -0.7951807228915663
-0.7951807228915663 x 100 = -79.52%