-99.8% is the change from 509 to 1
Calculation steps:
[( 1 - 509 ) ÷ 509] x 100 = -99.8%
Formula
Percentage change = [(1 - 509) / 509] x 100
Subtract the new number by the original number
1 - 509 = -508
-508 ÷ 509 = -0.9980353634577603
-0.9980353634577603 x 100 = -99.8%