-10.11% is the change from 900 to 809
Calculation steps:
[( 809 - 900 ) ÷ 900] x 100 = -10.11%
Formula
Percentage change = [(809 - 900) / 900] x 100
Subtract the new number by the original number
809 - 900 = -91
-91 ÷ 900 = -0.10111111111111111
-0.10111111111111111 x 100 = -10.11%
Example