-99.8% is the change from 511 to 1
Calculation steps:
[( 1 - 511 ) ÷ 511] x 100 = -99.8%
Formula
Percentage change = [(1 - 511) / 511] x 100
Subtract the new number by the original number
1 - 511 = -510
-510 ÷ 511 = -0.9980430528375733
-0.9980430528375733 x 100 = -99.8%