-79.01% is the change from 810 to 170
Calculation steps:
[( 170 - 810 ) ÷ 810] x 100 = -79.01%
Formula
Percentage change = [(170 - 810) / 810] x 100
Subtract the new number by the original number
170 - 810 = -640
-640 ÷ 810 = -0.7901234567901234
-0.7901234567901234 x 100 = -79.01%