Mastering Mind-bending Math Tricks (An In-depth Guide for Beginners)

Wow your audience with the power of math

Co-authored by Caroline Heiderscheit

Last Updated: February 13, 2023

Grab your cape and top hat, because you're about to create magic. Math magic! All of those math tricks you've seen performed by friends, teachers, and YouTubers...they're actually much easier to learn than you'd think. And you're in luck, because we're walking you through the most earth-shattering, life-changing, brain-exploding tricks below. Ready to impress your pals? Let's get started.

Method 1

Method 1 of 2:

Mind-Reading Math Illusions

$Image titled Read Someone's Mind With Math (Math Trick) Step 1$

1
Impress your audience with the "End With 3" trick. This trick is a good one to start with, as its one of the simplest. So what are you waiting for? Follow these steps to blow your friend's mind (and pro tip: it might help to give them a piece of paper if mental math might not be their strength).
- Ask an audience member to choose a number between 1 and 10.
- Tell your audience to multiply their number by 2.
- Ask the audience to multiply the new number by 5.
- Have the audience divide their current number by their original number.
- Instruct the audience to subtract 7 from their current number.
- Now it's your turn. If they did everything correctly, the answer will always be 3. Amazing!
- For example: if they choose 3, they'll do 3x2=6, 6x5=30, 30/3=10, and 10-7=3.
$Image titled Read Someone's Mind With Math (Math Trick) Step 2$

2
Perform the "Divide by Half" trick. This one's a little more complicated, but it's a perfect way to ramp up the excitement for your audience. This time, you'll have to choose a number too, specifically, an even number. Follow these steps:
- Ask your audience to choose a number between 1 and 10.
- Tell them to multiply their chosen number by 2.
- Choose an even number to use yourself and share it with your audience. Ask them to add your number to the one in their head.
- Tell your audience to divide the new number by 2.
- Tell them to subtract their original number from the equation.
- Next, blow their mind. The answer is half of the even number you chose initially.
- For example: if you choose 10, and your audience member chooses 3, the equations will be 3x2=6, 6+10=16, 16/2=8, 8-3=5, and finally, 5 is half of 10.
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3
Wow your friend with the "Lucky Number 13" trick. This great trick operates on the unique property of the multiples of 9. Here's how you'll impress your friend with simple math:
- Ask your audience to choose a number between 1 and 10.
- Tell them to multiply their number by 9.
- Ask them to add the first and second digit of their new number together. If it's a single digit number (i.e. 9), add 0.
- Get them to add 4 to their new number.
- Now, shock them with the final result! Their number should be 13.
- For example: If they choose 3, the equations will be 3x9=27, 2+7=9, and 9+4=13.
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4
Add some panache to your performance. While the most important thing is that you get the steps down right, you're ultimately performing a magic trick. Showmanship and style give your performance extra excitement, pizzaz! Try to speak in a confident, theatrical voice, lean into big hand gestures, and when you're done, refuse to share the magic behind your tricks.

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Method 2

Method 2 of 2:

Simple Number Tricks

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1
Blow friends' minds with the power of simple math. Math is filled with balance, patterns, and other awesome features. The tricks we walked you through above rely on those very patterns, but not all tricks have to be about mind-reading. If you can't get someone to pay attention for a full trick (or you don't feel like memorizing the schtick), then share some quick, magical mathematical moments instead.^{[1]
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- Multiply 6 by an even number. The answer will end in the number you multiplied by (6x4=24, 6x8=48).
- Repeat any number 3 times in your head (i.e., 777, 111, 444). Add up the digits, and divide your original number by the result of your addition. Your answer is 37!
- Start with a number between 1-6. Multiply by 9, then 111, then 1001, and then divide by 7. The result will astound friends: it'll always contain a 1, 2, 4, 5, 7, and 8.
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2
Surprise your friend with funny, numbers-based riddles. There are tons to try, and we've listed some of the best below. Though these don't involve math (or mind reading), they do create a funny gotcha moment that'll leave your friend feeling silly.^{[2]
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- How many 9s are in 100? Your friend might feel tempted to say "10," but in fact, the answer is 20.
- How many letters are in the alphabet? "The alphabet" has 11 letters.
- Your two coins equal 30 cents, and one of them isn't a quarter. Which coins do you have? A nickel and a quarter (the nickel is the coin that's not a quarter).
- There are eight oranges in a bag and you take away two. How many do you have? 2 of course! Specifically, the 2 that you took away.
- Some months have 8 letters in their name, some have 5. How many have 3? All of them have (at least) 3, duh!
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3
Show off with the first 7 letters of Pi. I know what you're thinking: yeah, I would if I could! But the truth is, you don't have to memorize those 7 numbers, you just have to recall a single sentence (How I wish I could calculate Pi). Say it to yourself a few times to burn it into your brain, and then, count the number of letters in each word.^{[3]
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- "How" = 3, "I" = 1, "wish" = 4, "I" = 1, "could" = 5, "calculate" = 9, "Pi" = 2. What do you end up with? 3.141592, or, the first 7 numbers of Pi.

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Community Q&A

Question

What if your trick is wrong?

wikiHow Staff Editor
Staff Answer
This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

wikiHow Staff Editor

Staff Answer

If your trick is wrong, that's okay. It just means that somewhere along the way, some of the math was done wrong. Try again with a pen & paper, and do the math carefully.
Question

How many times out of ten will these tricks work?

wikiHow Staff Editor
Staff Answer
This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

wikiHow Staff Editor

Staff Answer

10/10! If they don't work, it just means that the math wasn't done quite right. Try again!
Question

Will this work if I use big numbers (like 50 or 100)?

Community Answer

Yes, but it will make the math more complex. Using 1 through 10 is a lot easier.

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References

About This Article

Co-authored by:

Caroline Heiderscheit

wikiHow Staff Writer

This article was co-authored by wikiHow staff writer, Caroline Heiderscheit. Caroline Heiderscheit is a Staff Writer for wikiHow living in Santa Monica, CA. She has two years of experience working in content, including a year of editing work for first-time novelists. Caroline graduated from Stanford University in 2018 with degrees in American Studies and Creative Writing. This article has been viewed 1,308,951 times.

3 votes - 7%

Co-authors: 61

Updated: February 13, 2023

Views: 1,308,951

Categories: Magic Tricks | Mathematics

Article SummaryX

To read someone's mind with math, ask your partner to pick a number between 1 and 10. Tell your partner to multiply their number by 2, then multiply the new number by 5. Divide their current number by the original number, then subtract 7 from the answer. Finish by guessing the answer, which should always be 3. If you want to give your trick the appearance of being magical, wear a magician's costume and perform each step with a touch of theatrical flair. For tips on how to do the Divide by Half or Lucky Number 13 tricks, read on!

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