-9.01% is the change from 866 to 788
Calculation steps:
[( 788 - 866 ) ÷ 866] x 100 = -9.01%
Formula
Percentage change = [(788 - 866) / 866] x 100
Subtract the new number by the original number
788 - 866 = -78
-78 ÷ 866 = -0.09006928406466513
-0.09006928406466513 x 100 = -9.01%