-89.89% is the change from 900 to 91
Calculation steps:
[( 91 - 900 ) ÷ 900] x 100 = -89.89%
Formula
Percentage change = [(91 - 900) / 900] x 100
Subtract the new number by the original number
91 - 900 = -809
-809 ÷ 900 = -0.8988888888888888
-0.8988888888888888 x 100 = -89.89%