DRAGON QUEST XI – How to win the Roulette Jackpot.
-Speak to the bunny girl next to the jackpot pile. She should say something along the lines of someone winning the jackpot soon.
-If she doesn’t say that, Zoom to Octagonia, rest at the Inn and speak to her again. Repeat the same process until she does.
-Go to the 200 coins table, bet the max ammount on the numbers 12 and 14.
Make sure you get the quest to get a jackpot before doing this, as you can easily complete it with this method.
Credit goes to this GameFAQS topic