THAMNO

I received the following email message from a friend:

Don’t tell me your age; The Hershey Man will know!   YOUR AGE BY CHOCOLATE MATH     This is pretty neat.   DON’T CHEAT BY SCROLLING DOWN FIRST! It takes less than a minute . Work this out as you read . Be sure you don’t read the bottom until you’ve worked it out! This is not one of those waste of time things, it’s fun. 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.         chocolate Calculator.

Does it work, and if it does, how?
First of all, forget about the chocolate. It has nothing to do with chocolate. It’s just about numbers.

In step one, you are asked to choose a number from 2 (more than once) to 9 (less than 10):
      Result = Number

In step two, you must multiply this number by 2:
    Result = Number x 2

In step three, you must add 5 to this number:
    Result = Number x 2 + 5

In step four, you must multiply this number by 50:
    Result = (Number x 2 + 5) x 50

In step five, you must add 1759 if you already had your birthday, 1758 if you had not.
    Birthday is passed:
        Result = (Number x 2 + 5) x 50 + 1759
    Birthday is not passed:
        Result = (Number x 2 + 5) x 50 + 1758

In step six, you must subtract the four digit number of your birth year:
    Birthday is passed:
        Result = (Number x 2 + 5) x 50 + 1759 - Birthyear
    Birthday is not passed:
        Result = (Number x 2 + 5) x 50 + 1758 - Birthyear

The Result should now be a three digit number of which the leftmost digit is the number you chose at the start, and of which the rightmost two represent your age.

We can rewrite the calculations this way:
    Birthday is passed:
        Result = (Number x 2 x 50) + (5 x 50 + 1759) - Birthyear
    Birthday is not passed:
        Result = (Number x 2 x 50) + (5 x 50 + 1758) - Birthyear

Now, we can simplify it a bit, by actually performing some of the calculations:
    2 x 50 = 100
    5 x 50 + 1759 = 2009 (the year in which this message was written)
    5 x 50 + 1758 = 2008 (the previous year)

    Birthday is passed:
        Result = (Number x 100) + (2009 - Birthyear)
    Birthday is not passed:
        Result = (Number x 100) + (2008 - Birthyear)

Therefore, the calculations have the net result of multiplying your chosen number by 100, which has the visual effect of moving the digit two places to the left:
    2 x 100 = 200
    3 x 100 = 300
    and so on

If you already had your birthday, (2009 - Birthyear) will quite obviously give you your age, and so will (2008 - Birthyear) if you did no yet have your birthday.

Let’s say that you were born in 1987:
    2009 - 1987 = 22
    2008 - 1987 = 21

In this case, the numbers would be 222, 322… or 221, 321…

That seems obvious enough. So, yes the trick works. However, you’d better not be older than 99.

Are there limits to the trick?
Suppose you chose number 2, that you were born in 1909 and that your birthday has indeed passed. That would give you:
    Result = 2 x 100 + 2009 - 1909
Or:
    Result = 200 + 100 = 300

It now seems that you would have chosen number 3 and that you are zero years old. Therefore, the trick is not meant for those of us who have been blessed with a long life.

Is the trick too limited?
The mail states that the number we choose must be “more than once,” i.e. at least 2. This is correct, but excludes 1, and it will work just as well with 1. Assuming you were born in 1987 and that you already had your birthday:
    Result = 1 x 100 + 2009 - 1987
Or:
    Result = 122

Where 1 is your number and 22 is your age.

What to think of it?
The email states that:

“THIS IS THE ONLY YEAR (2009) IT WILL EVER WORK, “

This is obviously correct. It will not work in previous years, nor will it work in later years. It is easy enough to update it though. Instead of adding 1759 or 1758, adding 1760 or 1759 will work just fine for next year (2010), while adding 1761 or 1760 will work for the year after that (2011). I wonder if we will get those mails!

“SO SPREAD IT AROUND WHILE IT LASTS.”

This is typical for hoax emails. They also urge people to send their (usually) doom-and-gloom messages to everybody. However, this one, while somewhat obvious, is not a hoax. You may irritate some people with it, but it is not a lie, and some people may enjoy it. So, why not? If you know some people who like this type of stuff, don’t deprive them.