-97.3% is the change from 666 to 18
Calculation steps:
[( 18 - 666 ) ÷ 666] x 100 = -97.3%
Formula
Percentage change = [(18 - 666) / 666] x 100
Subtract the new number by the original number
18 - 666 = -648
-648 ÷ 666 = -0.972972972972973
-0.972972972972973 x 100 = -97.3%