Often beginning card counters have difficulty understanding how to use index numbers to vary basic strategy. Many books do not explain things clearly enough. Some books simply state that when the index number is reached then one should vary from basic strategy. For hit/stand index numbers, normally this means that when the true count reaches or exceeds a positive index number, then one should stand, but when the true count reaches or exceeds (ie is more negative than) a negative index number, then one should hit. A beginner can easily become confused when under pressure to make a play in the casino.

I prefer a method of using one rule for both positive and negative hit/stand index numbers. Stanford Wong's 1994 edition of "Professional Blackjack" is an excellent text to use for illustrating this method. However, let's take a look at some indices from the 1981 version of "Professional Blackjack" and compare them to the indices from the 1994 version. Then you will have a better idea of what I mean about understanding index numbers.

Looking at Table A1 in the 1981 edition, we see that the index number is -1 for 13 vs 2. On the other hand, looking at Table A1 in the 1994 edition, we see that the index number is 0 for 13 vs 2. How can that be?, you ask. How can there be two different index numbers for the same play? The answer is found when we look at the notes. In the 1981 edition, on p158 it says that "A number from a table means stand . . . if your count per deck is higher than the number. If your count per deck is lower than the number in the table, then hit . . .. If your count per deck is equal to the number, take your pick."

To illustrate this concept, let's take a look at the following number line.

{ . . ., -6, -5, -4, -3, -2, -1, 0, +1, +2, +3, +4, +5, . . . }

If we follow the instructions in the 1981 edition, then we would stand at a true count of 0, +1, +2, +3, or greater, and we would hit at a true count of -2, -3, -4, -5, or any larger negative number. At -1, we can choose either hit or stand.

Now, let's look at the notes in the 1994 edition. On p254, in the "KEY TO APPENDICES A AND B," we find that the index "number" means to "Stand . . . at a count per deck equal to or greater than the number; hit . . . at a count per deck less than the number.

The index number in the 1994 edition is 0, so this means that we should stand at a true count of 0, +1, +2, +3, or greater, and we would hit at a true count of -1, -2, -3, -4, -5 or any larger negative number.

If we choose to hit at -1, then we are really making the same play in spite of the fact that there are two different index numbers. However, to know this, the notes must be read and understood.

Let's try a second example. In the 1981 edition (Table A1) the index number for ten vs 9 is -1. In the 1994 edition, the index number for the same play is 0. But, now we know to read the notes. The notes to the 1981 edition basically tell us to double down if the count per deck is higher than the index number, don't double down (in this case hit instead) if the count per deck is lower than the index number and to take our pick when the ocunt per deck is equal to the index number.

So, this means that at a true count of 0, +1, +2, +3, +4, or greater, we would double down. At a true count of -2, -3, -4, -5, or any larger negative true count we would hit. And at a true count of -1, we could either double or hit.

In the 1994 edition, we should double if the count per deck is equal or greater than the index number and hit if the count per deck is less than the index number. Because the index number is 0, this means that we would double down at a true count of 0, +1, +2, +3, or greater and hit at a true count of -1, -2, -3, -4, or any larger negative true count.

So, if we are using the 1981 rules and choose to hit at a true count of -1, then again we are making the identical play. To be very clear on what your index numbers mean, please read the notes in the books you are learning them from.

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