-51.95% is the change from 668 to 321
Calculation steps:
[( 321 - 668 ) ÷ 668] x 100 = -51.95%
Formula
Percentage change = [(321 - 668) / 668] x 100
Subtract the new number by the original number
321 - 668 = -347
-347 ÷ 668 = -0.5194610778443114
-0.5194610778443114 x 100 = -51.95%