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Teach a math trick

Teach a math trick
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Learn a quick mental math trick to multiply by nine using finger patterns, practice examples, and explain why the trick works.

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Step-by-step guide to multiply by nine using finger patterns

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Learn 2 to 20 Times Multiplication Tricks for kids || Easy and fast way to learn || Table tricks

What you need
Paper, pencil, your hands

Step 1

Hold both hands up in front of you with your palms facing away and your fingers spread wide.

Step 2

Pick up your paper and pencil.

Step 3

Write the numbers 1 to 10 across the top of the paper from left to right.

Step 4

Line the paper under your hands so each finger matches one number on the paper.

Step 5

Choose a number from 1 to 10 that you want to multiply by 9.

Step 6

Fold down the finger that matches the number you chose.

Step 7

Count the fingers to the left of the folded finger out loud and remember that number as the tens digit.

Step 8

Count the fingers to the right of the folded finger out loud and remember that number as the ones digit.

Step 9

Write the tens digit first and then the ones digit on your paper to make the answer for your chosen number × 9.

Step 10

Try the problem 4 × 9 now by folding the 4th finger and using Steps 7–9 to find and write the answer.

Step 11

Try the problem 7 × 9 now by folding the 7th finger and using Steps 7–9 to find and write the answer.

Step 12

Read this explanation to learn why the trick works: 9 × n equals 10 × n minus n, so the fingers to the left of the bent finger equal n − 1 (the tens) and the fingers to the right equal 10 − n (the ones).

Step 13

Share your finished trick and what you learned on DIY.org

Final steps

You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!

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Help!?

What can we use if we don't have paper and a pencil to write the numbers 1–10 across the top?

Write the numbers 1–10 on a row of sticky notes, in a phone note, or draw them with chalk and then line that row under your hands as in Step 3 to match each finger to a number.

I folded the finger but got the wrong product—what probably went wrong and how do I fix it?

Make sure you matched the written numbers to the correct fingers in Step 3, folded the finger that matches your chosen number in Step 6, and counted fingers left for the tens and right for the ones per Steps 7–8.

How can I adapt this trick for younger or older children?

For younger kids, use numbers 1–5 and fold fingers on one hand while counting slowly through Steps 6–8, and for older kids have them write the 10×n − n explanation from the 'why it works' section and test all the 9× problems like in Steps 10–11 without folding.

How can we make the activity more fun or share our work?

Decorate your paper, use colored stickers to mark the tens and ones while following Steps 7–9, time how fast you can do each 9× problem, and make a short video to share on DIY.org as the instructions suggest.

Watch videos on how to multiply by nine using finger patterns

Here at SafeTube, we're on a mission to create a safer and more delightful internet. 😊

Multiplication Tricks for Kids | Multiplication by 0, 1, 2, 5, 9 and 10 | Times Tables Tips

4 Videos

Facts about mental math and arithmetic tricks

✨ For 9×1 through 9×10 the tens digit rises 0→9 while the ones digit falls 9→0, making a neat mirrored pattern (09,18,27,...,90).

🔢 Every multiple of 9 has digits that add up to a multiple of 9 (and repeated digit-summing brings you to 9).

📚 Finger-based math tricks have been used around the world for centuries as fast, hands-on mental math helpers.

🖐️ The classic 9× finger trick works by folding the finger for the multiplier — fingers to the left count tens, to the right count ones.

🧠 You can always get 9×n quickly by doing 10×n minus n — that is the simple subtraction idea behind the finger trick.

How do you teach the nine-times finger trick with examples and explanation?

Start by numbering ten fingers left-to-right 1–10. To do 9×n, fold down the nth finger. Count fingers left of the fold for tens and right for ones. Example: 9×3 → fold third finger → 2 left (20) and 7 right → 27. Practice 9×4→36, 9×7→63. Explain why: 9×n = 10×n − n, so folding shows taking one group of n away from the nearest ten.

What materials are needed for the 9 times finger trick?

No special materials are required—just both hands and a calm space. Optional extras include paper and pencil to record results, counters or beads to model tens and ones, and a printed finger-number chart for beginners. For online lessons, a webcam or camera helps children watch finger positions. Simple, familiar items make the activity easy to repeat at home or school.

What ages is the nine-times finger trick suitable for?

This trick suits children roughly aged 5–10 who are learning multiplication and place value. Younger children (about 5–7) may need modeling and manipulatives; older elementary kids (8–10) can understand the 10×n − n idea and work mentally. Adaptations like a paper chart or counters help learners with fine-motor or developmental differences. Pace practice to each child’s confidence and readiness.

What are the benefits of teaching the nine-times finger trick?

The finger trick builds number sense, strengthens mental math, and makes subtracting from ten tangible. It boosts confidence with quick wins, reinforces place-value understanding, and helps memorize times tables. Short, regular practice improves fluency and transfers to other strategies. The kinesthetic, visual method especially helps learners who benefit from hands-on approaches and reduces anxiety around multiplication.
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Teach a math trick. Activities for Kids.