THE JACK

twenty-one at the jackstaff
1,000
BET0
The dealer shows an ace. Insurance?
The dealer is at work…

The log

HandYouDealerBetNetPlayReplay

Your seamanship

The book

Computed in your browser a moment ago from the maths in jack.js — six decks, the dealer stands on soft 17 (a 17 with an ace counted as 11), double after split, late surrender. The highlighted cell is your hand right now.

HitStandDouble (else hit) Double (else stand)SplitSurrender (else hit)

Stats & achievements

How to play

Beat the dealer without going over 21. Cards 2–10 count their number, J/Q/K count 10, an ace counts 11 or 1 — whichever helps. An ace and a ten-card dealt together is a blackjack and pays 3 to 2.

  1. Bet. Tap chips to build your bet (it's kept between hands), then Deal.
  2. Play your hand. Hit takes a card. Stand keeps what you have. Double doubles the bet for exactly one more card. Split a pair into two hands (up to four), each with its own bet. Surrender gives up half the bet on your first two cards.
  3. The dealer plays by fixed rules: draws to 17 and stands on all 17s. Beat the dealer's total, or watch them bust, and you win even money.

The coach

The book is the best possible play for every hand — worked out by maths, not guesswork. For your first 15 hands of free play, the best button glows (the daily and drills are on your own — tap Hint if you must). Stray from it and the coach tells you what to do instead, why, and roughly how many chips the habit would cost you. Playing by the book raises your rank, from Landlubber up to Admiral. Tap 📖 to see the whole chart.

The count

The shoe plays down to a cut card, so the cards remember. Turn on the count trainer in settings to see the Hi-Lo running count (2–6 are +1, 7–9 are 0, tens and aces −1) and the true count (running count per deck left). At each shuffle you'll be quizzed on the running count.

Drills

Drills deal only the tricky spots, one decision at a time, with no money. Get a spot right three times in a row (without the hint) and it's mastered 🏅; spots you haven't mastered come up more often. My leaks deals the spots you miss most.

The daily shoe

Everyone gets the same cards today — about 30 hands, at a table with a 100-chip limit. Start with 1,000, play it through, and share how cleanly you played it. Same cards for all — the only difference is how you play and what you bet. Par is what flat 25s played by the book make from the same cards. Scores run on the honour system: the shoe is public maths, not a secret.

Keys

Space deal · H hit · S stand · D double · P split · R surrender · I/N insurance · B ask the book · 1–5 chips · ⌫ clear bet · C chart

Honest maths

With perfect play these rules give the house about 0.4%. Nothing here is rigged, and nothing here is real money: one seed shuffles each shoe, and every hand in the log replays card-for-card from that seed.

Settings

The cut card is out

Shore leave

Daily shoe