-3.44% is the change from 668 to 645
Calculation steps:
[( 645 - 668 ) ÷ 668] x 100 = -3.44%
Formula
Percentage change = [(645 - 668) / 668] x 100
Subtract the new number by the original number
645 - 668 = -23
-23 ÷ 668 = -0.0344311377245509
-0.0344311377245509 x 100 = -3.44%