-93.91% is the change from 509 to 31
Calculation steps:
[( 31 - 509 ) ÷ 509] x 100 = -93.91%
Formula
Percentage change = [(31 - 509) / 509] x 100
Subtract the new number by the original number
31 - 509 = -478
-478 ÷ 509 = -0.9390962671905697
-0.9390962671905697 x 100 = -93.91%