-99.8% is the change from 505 to 1
Calculation steps:
[( 1 - 505 ) ÷ 505] x 100 = -99.8%
Formula
Percentage change = [(1 - 505) / 505] x 100
Subtract the new number by the original number
1 - 505 = -504
-504 ÷ 505 = -0.998019801980198
-0.998019801980198 x 100 = -99.8%