# Calculate Your Age by Chocolate

Yes, it's true: if you are old enough to do mathematics and you like chocolate, you might be able to figure out your age (or someone else's) by starting with the number of times you like chocolate. By crunching these numbers (and a chocolate bar, if you’d like), your age is revealed at the end of the equation. Guess a friend's age through this fun magic trick!

## Contents

## Steps

### Chocolate Age Calculation Help

Doc:Chocolate Age Calculation Sheet

### Starting the Equation

- Pick the number of times a week that you want to have chocolate. That’s the starting point for figuring out your age by chocolate.
- This number should be more than one time per week but less than 10 times per week.
^{[1]}You could choose 1 or 10, too.^{[2]} - As an example, let’s use the number “7.” Figuring out someone’s age by chocolate is what is known as a parlor trick. It uses complexity to hide an outcome that is actually very simple.
- Try to be realistic here. How many times per week do you really want to have chocolate?

- This number should be more than one time per week but less than 10 times per week.
- Multiply the number by 2. You take whichever number of times you want to have chocolate per week and multiply it by 2. So far, so good!
- To continue our example, you would multiply 7 X 2 = 14.
- To use another example, let’s say that you said you wanted to have chocolate 3 times per week. Then, you would take 3 X 2 = 6.
- To repeat: Whichever number you picked for the number of times per week you want to have chocolate, you should multiply by 2. It’s a simple mathematical equation. Feel free to use a calculator if you need to, but so far you should be able to do the equations in your head.

- Add 5 to the last result. This means you should add 5 to whatever running total you have. It helps to write all of this down on a piece of paper as you go along.
- To use our first example, which started with 7, you now have 19. That’s because 14 + 5 = 19.
- To use the example starting with 3, you would now have 11. That’s because 6 + 5 = 11.
- If you are good at basic math, you should be able to easily calculate your age by chocolate. If not, grab the calculator. This is a fun way for children to master basic math equations, though.

### Continuing the Equation

- Grab the calculator. Up to this point, you’ve probably been able to calculate your age by chocolate in your head or using a pencil.
- At this point, though, the calculations are about to get a lot more complex! You should grab a calculator from the drawer.
^{[3]} - You can also find many calculators online, and most smart phones and laptops also have them built in if you don’t have a calculator online.
- Again, in an orderly fashion, write your answers on a piece of paper, likely vertically.

- At this point, though, the calculations are about to get a lot more complex! You should grab a calculator from the drawer.
- Multiply your number by 50. Whatever number you ended up with after you added 5 should now be multiplied by 50.
^{[4]}- To use our core example, in which you started out with 7, you would take 19 X 50. The answer is 950.
- To use our second example, in which you started out with 3, you would take 11 X 50. The answer is 550.
- The tricky part about figuring out your age by chocolate is to keep track of it all. If you get distracted by someone or something, you might lose your place and have to start over.

- Add a number based on the year to your total. For example, let's say you're doing the equation in 2016 (any year would work, though).
- To figure out the number you should use, take the current year minus 250 if you've already had your birthday in 2016. So, if you are doing the equation in 2016, take 2016-250=1,766.
- Let's say you are trying the calculation in 2017. You would take 2017-250=1,767 if you have already had your birthday in 2017.
- Add the number you get to your running total. To continue with our example of 7, presuming you are doing the calculation in 2016, you would add 950+1766=2716.

- Subtract one if you haven't had your birthday yet. If you haven't had your birthday, you need to take another point off the total.
- For example, if you haven't yet had your birthday in 2016, and that's the year you're performing the equation in, you would use the number 1,765.
- If performing the equation in 2017, you should also subtract another point if you haven't had your birthday yet. So you would use 1,766. The same is true of any year.
- Add the number you get to your running total.

### Completing the Equation

- Subtract the year you were born. This year should be four digits. Say 1970. Or 1988.
- Let’s continue with our example of 7, and use the 2,716 number you got above. Let’s say you were born in 1970.
- The answer would be 2,716-1970=746.
- Continuing with our example of 3, let’s go with the 2,315 number and say you were born in 1990. The answer would be: 325.

- Interpret the number. You should end up with a three-digit number (in our first example, we ended up with 746 and in the second example, we ended up with 325).
^{[5]}- The first digit (in the first example 7, and in the second example 3) was the number of times you like chocolate in the week.
- The last two digits (in the first case 46, and in the second case 25) are your age!
- Weird, huh? Now go eat some chocolate! It’s impossible to think about chocolate constantly and not want to eat some. For most people, anyway.

- Play the trick on a friend. The cool part is to guess a friend’s age by chocolate, rather than just doing the trick on yourself!
- Maybe pick an older relative or a teacher – someone whose age you don’t really know. It will work like magic!
- What the trick really does when you break it down is that it ends up having you subtract your birth year from the current year.
^{[6]} - The other numbers in the equation, though, are meant to distract you. That’s how the trick works! It’s simple but fun.

## Tips

- Check your calculations for any mistakes.
- This is a nifty trick for kids learning basic mathematics, who can practice it on adults and elicit reactions of surprise and amusement.

## Warnings

- Add the requirement to reveal whether a person's birthday has passed or not, and most knowing individuals will come to the conclusion that you are just using the chocolate to smokescreen the actual calculations taking place.
- This will not work consistently for people who are 100 years old or older.

## Sources and Citations

- http://www.murderousmaths.co.uk/games/choc/agebychoc.htm
- http://www.pleacher.com/mp/puzzles/tricks/agechoc.pdf
- http://www.onemathematicalcat.org/algebra_book/online_problems/Robin_Senseney_chocolate_math/why_choc_works.htm
- http://teachmama.com/chocolate-math-age-by-chocolate/
- https://thecriticalthinker.wordpress.com/2010/05/20/calculating-age-by-chocolate-math/
- http://www.romanticlovesecrets.com/Chocolate-Math-Test.html

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