-51.03% is the change from 631 to 309
Calculation steps:
[( 309 - 631 ) ÷ 631] x 100 = -51.03%
Formula
Percentage change = [(309 - 631) / 631] x 100
Subtract the new number by the original number
309 - 631 = -322
-322 ÷ 631 = -0.5103011093502378
-0.5103011093502378 x 100 = -51.03%