-33.7% is the change from 638 to 423
Calculation steps:
[( 423 - 638 ) ÷ 638] x 100 = -33.7%
Formula
Percentage change = [(423 - 638) / 638] x 100
Subtract the new number by the original number
423 - 638 = -215
-215 ÷ 638 = -0.33699059561128525
-0.33699059561128525 x 100 = -33.7%