I do this as well sometimes (if I have 890 in my wallet rather than 900, I just bet 10 -> 20 -> 40 to make it a round 900 (and then I play poker)). But note that this isn't +EV, it's just creating an asymmetry in probability (i.e., it's unlikely to go wrong) for an asymmetry in result (i.e., it's very bad if it goes wrong). E.g. if you're betting three times, then the odds of winning the 10$ are 7 to 1 (7/8 vs. 1/8) but the risk reward ratio is also exactly 1 to 7 (10$ vs. 70$). If you bet 6 times as in your example, the odds of it working are 63 to 1, but the risk/reward ratio is 10$ to 630$. (Ignoring the house edge for roulette.) If it goes wrong, you've blasted all the money you've come in with in the attempts of getting a free meal.