-79.05% is the change from 821 to 172
Calculation steps:
[( 172 - 821 ) ÷ 821] x 100 = -79.05%
Formula
Percentage change = [(172 - 821) / 821] x 100
Subtract the new number by the original number
172 - 821 = -649
-649 ÷ 821 = -0.7904993909866017
-0.7904993909866017 x 100 = -79.05%