-3.89% is the change from 668 to 642
Calculation steps:
[( 642 - 668 ) ÷ 668] x 100 = -3.89%
Formula
Percentage change = [(642 - 668) / 668] x 100
Subtract the new number by the original number
642 - 668 = -26
-26 ÷ 668 = -0.038922155688622756
-0.038922155688622756 x 100 = -3.89%