-3.92% is the change from 664 to 638
Calculation steps:
[( 638 - 664 ) ÷ 664] x 100 = -3.92%
Formula
Percentage change = [(638 - 664) / 664] x 100
Subtract the new number by the original number
638 - 664 = -26
-26 ÷ 664 = -0.0391566265060241
-0.0391566265060241 x 100 = -3.92%