-51.66% is the change from 664 to 321
Calculation steps:
[( 321 - 664 ) ÷ 664] x 100 = -51.66%
Formula
Percentage change = [(321 - 664) / 664] x 100
Subtract the new number by the original number
321 - 664 = -343
-343 ÷ 664 = -0.516566265060241
-0.516566265060241 x 100 = -51.66%