Very interesting idea Miss Tasha -- a side bet for roulette. I never play roulette so I don't know if there are side bets now. But I think the player would need to pay a fee (say $1) to have any of their numbers eligible for the "reverse" result.
But what if the roulette ball lands on a single digit? What's the reverse of 9? What if the ball lands on 39... is there a 93?