Perform a number prediction magic trick where you guide someone to pick numbers, do simple operations, and confidently reveal the hidden result.



Step-by-step guide to perform the Pick the Numbers Trick
Step 1
Write the number 4 on the small scrap of paper.
Step 2
Fold the scrap so the 4 is hidden.
Step 3
Put the folded scrap face down on the table.
Step 4
Ask a friend to think of any whole number between 1 and 100.
Step 5
Tell your friend to keep that number secret and remember it.
Step 6
Ask your friend to double their number by multiplying it by 2.
Step 7
Tell your friend to add 8 to the doubled number.
Step 8
Ask your friend to divide the new total by 2.
Step 9
Tell your friend to subtract their original number from that result and keep the final number secret.
Step 10
Open the folded scrap to reveal your prediction.
Step 11
Ask your friend if their secret result is 4 and celebrate the surprise.
Step 12
Share your finished magic trick on DIY.org
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!


Help!?
What can we use instead of a small scrap of paper if we don't have one?
Use a folded sticky note, business card, or torn notebook paper to 'Write the number 4' and 'Fold the scrap so the 4 is hidden' exactly like the instructions.
What if my friend gets the arithmetic wrong or forgets their original number during the steps?
Have them say each instruction aloud while you guide them through 'double your number,' 'add 8,' 'divide by 2,' and 'subtract your original number,' or let them use a calculator so the final secret will still be 4 when you 'Open the folded scrap to reveal your prediction.'
How can I adapt the trick for younger or older kids?
For younger kids use counters or fingers to demonstrate 'double their number,' 'add 8,' and 'divide by 2,' and for older kids let them swap the 'add 8' step for a different even number and predict the new result before you open the scrap.
How can we make the trick more impressive or personalized?
Decorate the 'small scrap of paper' with stickers, film your performance to 'Share your finished magic trick on DIY.org,' or change the 'add 8' step to another even number and write that new predicted result on the folded scrap for a custom reveal.
Watch videos on how to perform the Pick the Numbers Trick
Facts about number tricks and mental math
♟️ The ancient Lo Shu magic square (China) is a 3×3 grid where every row, column, and diagonal adds up to 15.
🔢 Classic trick formula — pick a number, double it, add 10, halve it, subtract the original number — you'll always end up with 5!
🎩 Famous mentalists like Derren Brown mix psychology and showmanship, but lots of impressive-looking effects are pure math.
🧠 Many number-prediction tricks are "self-working": clever algebra makes the answer predictable no matter the starting number.
🧮 Young children can follow these tricks easily because they only need basic operations: +, −, ×, and ÷.


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