-19.25% is the change from 800 to 646
Calculation steps:
[( 646 - 800 ) ÷ 800] x 100 = -19.25%
Formula
Percentage change = [(646 - 800) / 800] x 100
Subtract the new number by the original number
646 - 800 = -154
-154 ÷ 800 = -0.1925
-0.1925 x 100 = -19.25%