-21.07% is the change from 821 to 648
Calculation steps:
[( 648 - 821 ) ÷ 821] x 100 = -21.07%
Formula
Percentage change = [(648 - 821) / 821] x 100
Subtract the new number by the original number
648 - 821 = -173
-173 ÷ 821 = -0.21071863580998781
-0.21071863580998781 x 100 = -21.07%