-83.07% is the change from 821 to 139
Calculation steps:
[( 139 - 821 ) ÷ 821] x 100 = -83.07%
Formula
Percentage change = [(139 - 821) / 821] x 100
Subtract the new number by the original number
139 - 821 = -682
-682 ÷ 821 = -0.830694275274056
-0.830694275274056 x 100 = -83.07%