I believe you misunderstood my comment. Numbers who's origins are tainted by an illegal number can be illegal. Numbers who's origins do not have taint from an illegal number are not. It is not the number that is illegal, it is it's color. How it came into being, it's history, a permanent invisible mark that it carries with it, and transfers to whatever it touches.

You can't just dodge color by mutating the number via mathematical operations, color doesn't work like that. You can only get rid of the taint by using a fresh number without taint.