-83.19% is the change from 821 to 138
Calculation steps:
[( 138 - 821 ) ÷ 821] x 100 = -83.19%
Formula
Percentage change = [(138 - 821) / 821] x 100
Subtract the new number by the original number
138 - 821 = -683
-683 ÷ 821 = -0.8319123020706456
-0.8319123020706456 x 100 = -83.19%