Everyone has tried to guess someone’s age before. But if you’re a magician and you’re in a show, guessing someone’s age incorrectly will discredit your skills in front of your audience. If, however, you memorize this math-based trick, you will actually be able to tell anyone their age. All you need for this age guesser trick is a calculator.

To help people see your calculator, try to get one with big buttons and a big screen. That’s really for their benefit, not yours! You might even decide to show the calculator through a projector screen if you’re performing this in front of a large crowd.

## How It Works: Methods to Guess Someone’s Age Correctly

There are many ways you can perform the ‘guess her age’ challenge. The secret is that you are not guessing at all. In this article, we will go over a few methods, including the famous math-based trick. To the participant, it appears that you are performing a magic trick. But all you need to do is memorize these instructions and practice. The math is proven to work every time. Make sure to give clear instructions so you can get their birth month and year (without them realizing, of course).

### 1. Guess Someone’s Age Using a Selected Number

The first way to perform the age guess magic trick is through deduction with a selected number. You can perform this trick with a friend or stranger. Ask the participant to choose a number between one and ten. Once they have a number in mind, have them announce it. Let’s say they chose the number 7. Pause to tell them that you’re sorry, and you didn’t realize the math might be too hard for them, so you’ll get them a calculator.

Multiply the number they have chosen by two (e.g. 7 x 2 = 14). You can choose to do this math by hand or have a friend use a calculator to do the rest of the trick. Tell them that they must push the equals button on the calculator for every instruction you give.

Second, walk them through selecting their number and multiplying it by two again on the calculator. This is a great opportunity to build some humor into the act. Continue this humor by asking them to get ready for some big math before telling them to add 5 to their current value (14 + 5 = 19).

Then, move into the big math. Ask them to multiply the current number by 50 (19 x 50 = 950). Ask the participant if they have already celebrated their birthday this year. Did their birthday pass already? If so, you will add 1,769 to the prior result (e.g. 950 + 1,769 = 2,719). If not, then add 1,768 to the prior result (e.g. 950 + 1,768 = 2,718).

This number changes yearly, so here is a chart to reference:

2019: +1768 or +1769

2020: +1769 or +1770

2021: +1770 or +1771

2022: +1771 or +1772

After they add this number in, tell them not to say it out loud, but to subtract their birth year. Then, say “That’s it!” They’ll be confused because they will have a three-digit number far too large to be their age. You can act confused as well, and take the calculator from them.

Have them subtract the year they were born from these numbers without you looking (e.g. 2,718 – 1989 = 729). Look at the final answer. The first digit in place will be the original chosen number from the participant. The last two numbers will be the person’s age. So, the participant here would be 29 years old.

Put on a show sharing this information with the audience, and you’ve successfully guessed both their age and the number they chose at the start of the trick without hurting any feelings. At the end of it, people will think you are a mind reader. All it took was some simple math!

### 2. Guess Someone’s Age Using a Calculator

The second way to perform the age guessing game is by using a calculator. While the participant may need a calculator to perform the first act, this method is quite different. Start by asking the participant to multiply the first digit of their age by five. Let’s say that they are twenty years old (e.g. 2 x 5 = 10). Now, tell them to add three (e.g. 10 + 3 = 13). Have them double the resulting number (e.g. 13 x 2 = 26).

Now, have them add the second digit of their age to the resulting number (e.g. 26 + 0 = 26). Tell them to subtract six. This will be their current age (e.g. 26 – 6 = 20).

### 3. Guess Someone’s Birth Month and Date with a Calculator

Did you know that you can also use a calculator to deduce someone’s date and month of birth? This is a fun way to take the let’s ‘guess your age’ magic trick up a notch.

Start by entering the number seven in the calculator. Then, have the participant multiply the number seven by their birth month. Let’s say their birth month is May (e.g. 7 x 5 = 35). Remember not to look at the calculator. You don’t want the person (or audience) to think that you are cheating.

Now, subtract one from that number (e.g. 35 – 1 = 34). Multiply the resulting number by thirteen (e.g. 34 x 13 = 442). Have them add the day of their birth (e.g. 442 + 28 = 470) and then add three (470 + 3 = 437). Multiply the new number by eleven (437 x 11 = 5,203). Subtract the month of their birth (5,203 – 5 = 5,198).

Now, subtract the day of their birth (5,198 – 28 = 5,170) and divide by ten (5,170 / 10 = 517). Add eleven (517 + 11 = 528). Divide by 100 (528b / 100 = 5.28). The first digit before the decimal is their birth month (5 = May). The two digits after the decimal point is their birth day (28 = birth day).

## Have you Heard About the Artificial Intelligence Age Guesser?

Nowadays, the sophistication of technology is moving at a surprisingly rapid rate. You may have heard that a few years ago, Amazon and Microsoft both released an artificial intelligence picture age guesser. You choose to either upload a picture of yourself or take a selfie. The device scans your photo and through face detection, assesses your age. We wondered how accurate the age guesser is. So naturally, we had to try it out for ourselves.

After reading multiple reviews and experimenting with the software ourselves, we did not find it to be accurate. The software will make different estimates for your age based upon nuances like your facial expression and the angle from which the photo was taken. For magicians, we would stick with the math-based age guesser tricks to accurately gauge someone’s age. Don’t try to take a shortcut and use image software first.

## Brush Up on Your Math Skills and Memorize these Formulas

We get that math is not everyone’s strong suit. That is why we are so excited to share these formulas. All you need to do is practice and use a standard calculator to perform this age guessing trick accurately. Make sure to memorize the formulas before you try it out on a stranger or perform in front of a small audience. With repetition and dedication, you are on your way to becoming a good magician.

## Watch it in action!

Watch the same magic trick you learned above, and see how it works on you!