Wouldn’t that give you 11-100? l The Lowest number on a dice is 1, and 1×10 gives you 10.
The formula would have to be
((d10-1)×10)+d10=x≥90⟹y=(y+1)⟹z>1(d2)
So you’d still have to flip a coin on reaching a result of 90+ in order to know if you add a +1 or not as well or else you can’t get 90 as a result either.
(This is assuming you have a d10 that’s 1-10 btw and not 0-9!)