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Ten Twenty
Introduction
Ten Twenty is a blackjack side bet that wins if the player's first two cards sum to 10 or 20. The first placement I'm aware of was at the Macau Entertainment Complex in Cork, Ireland.
Rules
For purposes of the Ten Twenty side bet, all cards are counted as in blackjack, except aces are always 11. Wins are based on the player's initial two cards, as follow:
- Pair of fives: pays 22 to 1.
- All other two-card totals of 10: 10 to 1.
- All two-card totals of 20 (including ace-9): pays 3 to 1.
Analysis
The following table shows my analysis for six decks. The lower right cell shows a house edge of 5.39%.
Ten Twenty — Six Decks
| Event | Pays | Combinations | Probability | Return |
|---|---|---|---|---|
| 5-5 | 22 | 276 | 0.005689 | 0.125155 |
| Other total of 10 | 10 | 1,728 | 0.035617 | 0.356171 |
| Total of 20 | 3 | 5,136 | 0.105862 | 0.317586 |
| All other | -1 | 41,376 | 0.852832 | -0.852832 |
| Total | 48,516 | 1.000000 | -0.053920 |
Following is the house edge for various numbers of decks.
Ten Twenty — House Edge Summary
| Decks | House Edge |
|---|---|
| 1 | 8.75% |
| 2 | 6.72% |
| 4 | 5.72% |
| 6 | 5.39% |
| 8 | 5.23% |