-17.15% is the change from 991 to 821
Calculation steps:
[( 821 - 991 ) ÷ 991] x 100 = -17.15%
Formula
Percentage change = [(821 - 991) / 991] x 100
Subtract the new number by the original number
821 - 991 = -170
-170 ÷ 991 = -0.1715438950554995
-0.1715438950554995 x 100 = -17.15%