Granville's Bingo Strategy: The Balanced-Card System, Explained and Tested

Granville’s system is the other big card-picking strategy in bingo, usually mentioned right after Tippett’s theory. It comes from a famous name in a very different field: Wall Street. Here’s what the system says and what the math says back.

Who was Joseph Granville?

Joseph E. Granville (1923–2013) was an American stock market analyst and newsletter writer. He published the Granville Market Letter from 1963 until shortly before his death, and he’s credited with developing on-balance volume (OBV), a technical indicator traders still use. In the 1970s and early 1980s, his bearish calls were known for moving the market.

He also wrote about bingo. Library records list How to Win at Bingo by Joseph E. Granville, published by Parker Publishing Co. in 1977. That book is the source of what bingo sites now call “Granville’s strategy.” We haven’t been able to review a copy, so the summary below reflects how the system is consistently described rather than direct quotes.

What does Granville’s strategy say?

It says the numbers drawn in a game tend to spread out evenly, so you should choose cards whose numbers are spread out evenly too. The system is usually summarized as three rules:

1. Balance odd and even. Choose cards with about as many odd numbers as even numbers.
2. Balance high and low. Choose cards with about as many high numbers as low ones.
3. Balance final digits. Choose cards whose numbers end in a wide spread of digits (1, 2, 3 and so on), avoiding cards with several numbers that end in the same digit.

The reasoning is that over a game, the called numbers will include a fair mix of odds and evens, highs and lows, and each final digit. A card built the same way should, the theory goes, be “in step” with the draw.

Is the draw really balanced?

On average, yes. If you draw many balls at random from 1 to 75, you’ll usually get close to half odd and half even, and a fairly even spread of final digits. That’s just what random sampling does.

But the pool itself isn’t perfectly balanced. We counted the numbers 1 to 75:

And a card has 24 numbers, which can’t split evenly across ten final digits. So no card can be perfectly “balanced” in Granville’s sense anyway.

Does Granville’s strategy work?

No. Balance in the draw is a property of many numbers taken together. It says nothing about which specific numbers will be called next, and a bingo card wins only when its specific numbers are called.

Here’s the key fact: in a fair game, the chance that a card completes a pattern depends only on how many squares the pattern needs. Four corners needs four numbers. Any four numbers have exactly the same chance of all being called within, say, 30 balls: 2.25%. It doesn’t matter if they’re 2, 4, 6 and 8 (all even, all low) or 7, 22, 49 and 70 (nicely mixed).

When we simulated a million draws for our Tippett test, sets of very different numbers produced the same results within random noise. The same logic applies to odd/even and final-digit balance. Our bingo odds guide shows the exact formula.

The “due number” trap

Some versions of the system go further during play: if no number ending in 7 has been called yet, a 7-ending number is “due.” This is the gambler’s fallacy, the belief that a random process corrects itself in the short run.

Bingo balls have no memory. If 20 balls have been drawn and none ended in 7, the seven 7-ending balls are still in the machine among the 55 left. Each remaining ball has the same 1-in-55 chance of being next. A 7-ending number is no more likely than any other.

Why did a market analyst think this would work?

We can only guess, but the connection is easy to see. Technical analysis looks for patterns and balance in price and volume data, and Granville was known for confident rules built on those patterns. Applying that kind of thinking to bingo produces a system that feels logical. The difference is that bingo draws are independent and random by design, so there’s no pattern to exploit.

Is there any harm in using it?

Not if it’s just for fun. Picking balanced cards costs nothing and won’t hurt your chances. It also won’t help them. The problems start if a system makes you:

• spend more on “better” cards,
• skip a session because you didn’t get the cards you wanted, or
• believe you’re owed a win.

If you want strategies that really change your odds, there are only two: play more cards or play when fewer cards are in the room. Our bingo strategy tips and how many bingo cards to play guides explain both. For more beliefs put to the test, see bingo myths debunked.