-62.82% is the change from 831 to 309
Calculation steps:
[( 309 - 831 ) ÷ 831] x 100 = -62.82%
Formula
Percentage change = [(309 - 831) / 831] x 100
Subtract the new number by the original number
309 - 831 = -522
-522 ÷ 831 = -0.628158844765343
-0.628158844765343 x 100 = -62.82%