Edward Thorpe and the Ten Count System

Ten Count System Fundamentals
Pros and Cons of the Ten Count System

Written by Ian Mac

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, | Updated: October 1, 2026

The origins of card counting have been debated for several decades, with the first ace counters observed in Las Vegas casinos during the 1940s and 1950s. However, the first card-counting system that was mathematically proven effective was the so-called Ten-Count System, presented by researcher and mathematician Edward Thorp in his 1962 book, Beat the Dealer.

Edward Thorp, known today as the father of card counting, was a professor of mathematics and finance, as well as a blackjack player and researcher. Using the computational power of some of the earliest computers, he developed successful models for card counting. He later applied his methods in casinos and managed to profit from them, although he claimed that his goals were purely scientific. Before him, only a few counters had managed to gain an advantage over the casino without cheating. However, there were no sophisticated counting systems, and his method for tracking the cards on the table revolutionized the game of blackjack.

Following years of mixed success for advantage players in casinos, Thorp’s book demonstrated that it was possible to beat the house at its own game. By combining a blackjack strategy with a specially designed system for counting the 10-value cards in the deck, players could shift the odds in their favor.

Basics of the Ten Count System

How to Use Edward Thorpe’s Ten Count System

Basics of the Ten Count System

When Edward Thorp first demonstrated the Ten-Count System in the 1960s, it was groundbreaking. For the first time, a method for beating casinos was supported by clear mathematical evidence. By today’s standards, however, the system is extremely simple and easy for casinos to counter. More importantly, it has little practical relevance because it was designed for single-deck games.

Casinos now rarely offer single-deck blackjack, and when they do, they take specific countermeasures to prevent players from using Thorp’s counting method. So, what exactly is his system, and how does it differ from more advanced methods?

As with other counting systems, the Ten-Count System assigns different values to the cards and requires the player to keep a running count during play. Skilled counters can then adjust their strategy and bet size based on that count. Thorp’s system focuses on 10-value cards, which is the source of its name: all 10s, Jacks, Queens, and Kings are assigned a value of -9, while all other cards, from Ace through 9, are counted as +4.

The principle behind this method is that 10-value cards favor the player because they help form powerful hands, including blackjack, or a natural 21, and a total of 20. At the start of a single-deck game, there are 16 ten-value cards, and the system essentially tracks the likelihood of receiving one at any point in the game.

How to Use Edward Thorpe’s Ten Count System

Because 10-value cards are counted as -9 and all other cards as +4, players subtract 9 whenever a 10, Jack, Queen, or King is dealt and add 4 for any other card. It sounds simple, but players must learn to perform this basic math very quickly while playing. For example, suppose the following cards are dealt in the first round: the first player receives A-3, the second gets 8-6, and the dealer’s upcard is a Queen. The count would be 4 + 4 + 4 + 4 – 9, or 7.

The Ten-Count System does not specify when to increase or decrease a bet, or by how much. It only suggests increasing the stakes near the end of the deck if the count is positive. If the count drops below zero, players should reduce their wagers. Every playing decision should still follow basic strategy.

A variation of the method requires players to keep two separate counts instead of one. This is more challenging, especially for beginners, but the principle is straightforward. The game starts with 16 high cards (10 through King) and 36 low cards (Ace through 9). Players keep one count for the high cards and another for the low cards. Whenever a 10-value card appears, they subtract 1 from the high-card count. When a low card is dealt, they subtract 1 from the low-card count.

The concept may seem confusing at first, but it is simple in practice. If the player receives A-6 in the first round against a dealer’s 8, for example, the high-card count remains 16 while the low-card count drops to 33. If the low-card count drops to zero or close to it, the player should bet the table maximum. If the high-card count falls sharply, the bet should be reduced to the minimum.

Advantages

Disadvantages

The most obvious advantage of this card counting system is its simplicity – even if players keep two counts simultaneously. The method can be learned almost immediately and it could be applied without mistakes by most blackjack players. In comparison, the majority of systems developed after that could be extremely complex and hard to apply in real-life games.

While the Ten Count System was proved to be working in the 1960s, today, it is practically obsolete. Edward Thorpe invented it for single-deck games only, which were quite popular in casinos back then. However, modern blackjack variations are usually played with 4 to 8 decks of cards and the Ten Count method simply does not work.

The other great aspect of the Ten Count System is that it is effective in demonstrating when the deck is rich in high or low cards. This helps players adjust their bet size so they win more whenever the odds of the game are in their favor.

Even in single-deck games, we are now offered less favorable rules than what was a standard once – only a few rounds are played before a reshuffle and the deck is never dealt to the last card. This means that a counter using this method will almost never see the odds shift in his favor. Even if one or two cards remain in the deck, the outcome would be very different than the original calculations made by Thorpe.

The Ten-Count System is a method that every card counter should study, not because it is particularly effective, but because it helps players understand the fundamental idea of card counting and the importance of the 10-value cards in the deck. However, it is not suitable for multi-deck games with restrictions on doubling, resplitting aces, and other modern variations of the standard rules of the game. Overall, it can be useful for practice, but it should not be used for real-money play in casinos.

Ten Count System Fundamentals

Basics of the Ten Count System

How to Use Edward Thorpe’s Ten Count System

Advantages and Disadvantages of the Ten Count System