You measure the odds in a casino game by the house edge. That’s a long-term estimate of how much you’re expected to lose on each bet. In blackjack games, including Costa Rica rummy, the house edge assumes you’re playing the game with optimal strategy.
That’s called basic strategy.
In Costa Rica rummy, the house edge is 1% if you play with perfect basic strategy.
That’s a great number — the casino games with the worst odds have a house edge over 30%.
Most gamblers deviate from basic strategy on a hunch or because they don’t have it memorized.
This adds between 2% and 4% to the house edge, so it’s in your interesting to memorize basic strategy.
Luckily, for rummy blackjack, basic strategy is easy:
Splitting
The 1st task is to see if you have a hand you can split. This means you must have a pair. You’ll never split these pairs:
2s
3s
4s
5s
10s
You’ll split the following pairs in the following situations:
6s if the dealer has a 5 or 6 showing
7s if the dealer has a 4, 5, or 6 showing
8s if the dealer has an 8 or lower showing.
9s if the dealer has a 9 or lower showing (with the exception if the dealer has a 7)
aces unless the dealer has an ace showing
Hard and Soft Hands
If you don’t have a pair, you play your hand based on whether you have a hard or soft total. A soft total is one in which you have an ace that you can count as 1 or 11.
If you don’t have an ace, or if you have an ace that must count as 1 to keep from busting, you have a hard hand.
Here’s how you play your soft hands:
Always hit a soft 12 or lower.
Hit a soft 13 unless the dealer has a 5 or 6 — in those cases, double down.
Hit a soft 15 or 16 unless the dealer has a 4, 5, or 6 — in those cases, double down.
Also, hit a soft 17 unless the dealer has a 3, 4, 5, or6.
Stand on a soft 17 unless the dealer has a 9 or higher, in which case, hit.
Always stand on a soft 19 or higher.
Here’s how you play your hard hands:
Always hit any hard total of 8 or lower.
Hit a hard 9 unless the dealer has a 3, 4, 5, or 6 — in that case, double down.
Double down on a hard 10 or 11 unless the dealer has a 10 or ace — in that case, just hit.
Hit a hard 12 if the dealer has a 2, 3, 7, 8, 9, or 10. Otherwise, stand.
Stand on a hard 13, 14, 15, or 16 if the dealer has a 6 or lower. Otherwise, hit.
Always stand on a hard 17 or higher.
If you want to learn more about the house edge, check out Tim’s post about how expected value can be negative or positive.
You can decide how much money to bring to the casino by understanding the game, the house edge, and its volatility. Read more about that here.
Where to Go Next
If you want a more detailed basic strategy with no mistakes, visit the Wizard of Odds page on the subject. He offers a convenient colored strategy table.
Conclusion
That’s about everything you could hope to want to know about what a rummy in blackjack is. That covers both the side bet that’s often available at sports books. And it also covers the Costa Rica game that’s supposed to be a substitute for real blackjack.
