-21.02% is the change from 509 to 402
Calculation steps:
[( 402 - 509 ) ÷ 509] x 100 = -21.02%
Formula
Percentage change = [(402 - 509) / 509] x 100
Subtract the new number by the original number
402 - 509 = -107
-107 ÷ 509 = -0.21021611001964635
-0.21021611001964635 x 100 = -21.02%