I recently received one of those emails that contains an incredible mathematical formula which magically calculates your age by starting with a totally unrelated number.

Here’s the formula (in the wording from the email).

1: First of all, pick the number of times a week that you would like to have chocolate (more than once but less than 10)

2: Multiply this number by 2 (just to be bold)

3: Add 5

4: Multiply it by 50 — I’ll wait while you get the calculator

5: If you have already had your birthday this year add 1759 .. If you haven’t, add 1758

6: Now subtract the four digit year that you were born

You should have a three digit number

The first digit of this was your original number (i.e., how many times you want to have chocolate each week)

The next two numbers are YOUR AGE! (Oh YES, it is!!!!!)

THIS IS THE ONLY YEAR (2009) IT WILL EVER WORK, SO SPREAD IT AROUND WHILE IT LASTS.

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Is that amazing?

If you think that it is, think again.

The arithmetic is ludicrously basic, but is wrapped up in a way that disguises this fact.

I’ll go through the arithmetic in a moment, if you’re at all interested – however, the main reason that I’m featuring this magical calculation here is because it’s a very good example of something that’s incredibly simple but that people mistake for being just plain incredible (and even inexplicable).

It follows a pattern that is common to many seemingly inexplicable phenomena (such as magic tricks). The power behind such phenomena lies in no small part in the fact that not only do people mistake them as being mysterious, but they actively *like* them to be mysterious. They deliberately look no further than the surface. After all, who wants a simple explanation when you can go “Wow!” instead?

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Here’s the arithmetic of the calculation.

1: Pick the number of times a week that you would like to have chocolate

Let’s say 6

2: Multiply this number by 2

6 x 2 = 12

3: Add 5

That’s 12 + 5 (I’ll leave these two numbers separate rather than adding them together right now – you’ll see why in a moment)

4: Multiply it by 50

I’ll multiply the 12 and the 5 from the previous step individually, which gives us 600 + 250

5: If you have already had your birthday this year add 1759

That gives 600 + 250 from the previous step, plus 1759. I’ll add the 1759 to the 250 now, keeping the 600 separate. 1759 + 250 = 2009. That gives 600 + 2009

6: Now subtract the four digit year that you were born

I’ll subtract the year of my birth, which is 1952, from the number 2009. That gives me 57

I’ve ended up with the number 600 + 57.

I’ll now finally add the two numbers together, which gives me 657.

Now, the formula states that, amazingly “The first digit of this was your original number (i.e., how many times you want to have chocolate each week). The next two numbers are YOUR AGE! (Oh YES, it is!!!!!).

It’s true: I started with the number 6, and my age is 57.

How amazing is that?

One of the tricks in this formula is that it makes you think that the number that you started with, for the amount of chocolate, is significant in calculating your age. It isn’t. In my example above I kept the chocolate part of the equation separate to the age part. The chocolate part is the part on the left of the + sign (so at step 3 above, where I got 12 + 5, the 12 is the chocolate part and the 5 the age part).

Looking more closely at the chocolate part of the equation here’s what you’ve been asked to do.

Think up a number

Multiply it by 2

Then multiply it by 50

That’s just a disguised way of saying “Think up a number and multiply it by 100”

In my case it was 6 x 100, which is 600

Think up a number, multiply it by 100, and hey presto, the first digit is the same as the number you first thought of!! No mystery there I’m afraid.

Now for the age part of the equation

Again, a simple bit of disguise obscures the incredible simplicity of the arithmetic

You’re asked to start with the number 5 (Step 3).

Then multiply it by 50

This gives 250

Then add 1759

This gives 2009. This just happens to be this year’s date (at the time of writing).

Then subtract the year of your birth.

Which, of course, gives you your age.

The trick here is that the number 2009 never appears as such in the equation, having been arrived at by a simple process of multiplying or adding other numbers. If you’d been asked directly to subtract your birth year from this number the arithmetic would be transparent.