-25% is the change from 668 to 501
Calculation steps:
[( 501 - 668 ) ÷ 668] x 100 = -25%
Formula
Percentage change = [(501 - 668) / 668] x 100
Subtract the new number by the original number
501 - 668 = -167
-167 ÷ 668 = -0.25
-0.25 x 100 = -25%
Example