-1.09% is the change from 829 to 820
Calculation steps:
[( 820 - 829 ) ÷ 829] x 100 = -1.09%
Formula
Percentage change = [(820 - 829) / 829] x 100
Subtract the new number by the original number
820 - 829 = -9
-9 ÷ 829 = -0.010856453558504222
-0.010856453558504222 x 100 = -1.09%