-9.99% is the change from 911 to 820
Calculation steps:
[( 820 - 911 ) ÷ 911] x 100 = -9.99%
Formula
Percentage change = [(820 - 911) / 911] x 100
Subtract the new number by the original number
820 - 911 = -91
-91 ÷ 911 = -0.09989023051591657
-0.09989023051591657 x 100 = -9.99%