-20.24% is the change from 509 to 406
Calculation steps:
[( 406 - 509 ) ÷ 509] x 100 = -20.24%
Formula
Percentage change = [(406 - 509) / 509] x 100
Subtract the new number by the original number
406 - 509 = -103
-103 ÷ 509 = -0.20235756385068762
-0.20235756385068762 x 100 = -20.24%