-51.58% is the change from 663 to 321
Calculation steps:
[( 321 - 663 ) ÷ 663] x 100 = -51.58%
Formula
Percentage change = [(321 - 663) / 663] x 100
Subtract the new number by the original number
321 - 663 = -342
-342 ÷ 663 = -0.5158371040723982
-0.5158371040723982 x 100 = -51.58%