BrightKidz Library
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Ten fingers held up with the third one folded down Two hands held up side by side, palms towards you, with the thumbs angled inwards. Counting from the left, the third finger has been folded down so there is a gap where it should be. A bracket above groups the two fingers before the gap, and a longer bracket groups the seven fingers after it.

The 9-Times Table Trick

About 4 minutes

Hold up both hands, and your fingers can give you any answer in the 9-times table from 9 x 1 to 9 x 10, no memorizing required.

The Finger Trick

Here's how it works:

  1. Hold both your hands in front of you, with your fingers spread out.
  2. To multiply 9 by a number (let's say 3), count that many fingers from the left (1, 2, 3).
  3. Bend that finger down (the 3rd finger in our example).
  4. Count the fingers before the bent finger. In our example, there are 2 fingers before the bent finger. This is the "tens" digit (20).
  5. Count the fingers after the bent finger. In our example, there are 7 fingers after the bent finger. This is the "ones" digit (7).
  6. Put the tens and ones together: 2 and 7 makes 27. So, 9 x 3 = 27.

Why Does This Work?

This works because of how our number system is set up. Each time you go up by one in the 9-times table, the tens digit goes up by one and the ones digit goes down by one. Your fingers are simply a way to track that pattern by hand.

Try It Out

Use the finger trick to solve these problems:

Check the middle one against your hands:

For 9 x 7 you bend the 7th finger. Six fingers stand before it and three stand after. What is the answer?

The other two come out at 45 and 81 — bend the 5th finger and you get 4 before and 5 after, bend the 9th and you get 8 before and 1 after.

Once you've done a few by hand, watch for the pattern without your fingers: for 9 x n, the tens digit is always one less than n, and the two digits always add up to nine.

Where the Trick Comes From

Lay out rows of ten, then take one cell out of every row. Three rows of ten is thirty, and taking three away leaves twenty-seven. That is all nine times anything ever is. Pack what is left back into tens and the ink stops one whole row short of what you laid, with a short row over — the row count is your tens digit and the short row is your ones digit. The last round goes past ten rows, where the finger pattern falls over and the taking away carries straight on.