-2.56% is the change from 820 to 799
Calculation steps:
[( 799 - 820 ) ÷ 820] x 100 = -2.56%
Formula
Percentage change = [(799 - 820) / 820] x 100
Subtract the new number by the original number
799 - 820 = -21
-21 ÷ 820 = -0.025609756097560974
-0.025609756097560974 x 100 = -2.56%