-89.91% is the change from 991 to 100
Calculation steps:
[( 100 - 991 ) ÷ 991] x 100 = -89.91%
Formula
Percentage change = [(100 - 991) / 991] x 100
Subtract the new number by the original number
100 - 991 = -891
-891 ÷ 991 = -0.8990918264379415
-0.8990918264379415 x 100 = -89.91%