-51.14% is the change from 657 to 321
Calculation steps:
[( 321 - 657 ) ÷ 657] x 100 = -51.14%
Formula
Percentage change = [(321 - 657) / 657] x 100
Subtract the new number by the original number
321 - 657 = -336
-336 ÷ 657 = -0.5114155251141552
-0.5114155251141552 x 100 = -51.14%