-20.51% is the change from 668 to 531
Calculation steps:
[( 531 - 668 ) ÷ 668] x 100 = -20.51%
Formula
Percentage change = [(531 - 668) / 668] x 100
Subtract the new number by the original number
531 - 668 = -137
-137 ÷ 668 = -0.20508982035928144
-0.20508982035928144 x 100 = -20.51%