🎂 The Birthday Mind Reader

The Birthday Mind Reader for kids: the whole trick

Somebody does a string of sums on a calculator starting from the day of their birthday. They tell you the answer. You tell them their birthday, day and month. It's a level 2 conjurer trick for ages 8 to 13 (grades 3rd–7th), takes 10 minutes to learn, and needs one thing you already have. Flick, the shop's rabbit, reads every step aloud with a picture, so a child can follow it alone.

The secret

The sums wrap the day and the month up into one number in a way you can unwrap. Take 165 off what they tell you and the day and the month fall out of the digits.

What you need

• A calculator, or a calculator app

How to do it

1. Ask them to key the day of their birthday into the calculator.
2. Times it by 5, then add 6.
3. Times that by 4, then add 9.
4. Times that by 5, then add the number of their birthday month.
5. Ask for the answer, take 165 off it in your head, and read their birthday out.

Magic words to say

“I'm not going to ask you when your birthday is. I'm going to ask you to do some sums, which is much worse, and then I'm going to tell you.”

Pro tips

• Practise taking 165 off a four-digit number in your head. That is the only hard part and it comes quickly.
• Let them key it in themselves and do not look at the screen. You only ever hear the final number.
• Pause before you say the date. Say the month first, then the day, as though it is arriving slowly.

If something goes wrong

If the answer comes out silly, they missed a step. Say "someone's calculator is fibbing" and run it again more slowly. It never fails twice.

Safety notes

• Only from the front.
• No fire, no flames and nothing sharp in a child's hand anywhere in the Magic Shop. Nothing ever goes in a mouth, a nose or an ear.

Why it works

Every step multiplies what is already there and adds a little more, so the day ends up multiplied by a hundred and the month is added on the end untouched. The spare bits add up to 165 every single time, whoever is playing, so taking 165 away leaves the day in the hundreds and the month in the units.

What kind of trick is this?

🔮 Prediction. You knew all along, or you read their mind. Almost every trick ever invented is one of eight kinds, and knowing which one you're watching is how magicians work out how a new trick is done.

The skill it teaches: Your magician name. Every magician has a stage name and a style. Perform it and it counts towards the Mind Reader badge.

Questions about the birthday mind reader

Are there magic tricks with a calculator or phone?

Yes. The Calculator Prediction fills a whole screen with your friend's favourite digit, nine times over, after a single multiplication. Any calculator works, including the app on a grown-up's phone.

How do magicians read minds?

They don't hear your thoughts. Mind-reading tricks use maths that always lands on the same answer, a secret peek, or a code agreed with a partner beforehand. Magicians who do mind tricks are called mentalists.

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