-38.51% is the change from 831 to 511
Calculation steps:
[( 511 - 831 ) ÷ 831] x 100 = -38.51%
Formula
Percentage change = [(511 - 831) / 831] x 100
Subtract the new number by the original number
511 - 831 = -320
-320 ÷ 831 = -0.3850782190132371
-0.3850782190132371 x 100 = -38.51%