Mind Your Decisions

Your Age by Diner & Restaurant Math–Why the Math Works

The trick

Here’s one of those fun math tricks I got in the email.

Don’t tell me your age; you probably would tell a falsehood anyway-but your waiter may know!

YOUR AGE BY DINER & RESTAURANT MATH

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 go out to eat (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

5. If you have already had your birthday this year add 1758…If you haven’t, add 1757.

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 go out to restaurants in a week.)

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

THIS IS THE ONLY YEAR (2008) IT WILL EVER WORK, SO SPREAD IT AROUND WHILE IT LASTS

Why it works

To take all the fun out of it, here’s the math behind the trick:

And to generalize

The trick is making the “special number” and 250 add up to the current year. This is why the later subtraction of the birth year reveals the person’s age. The special number depends on whether the birthday has happened.

For 2008, the special number is 1757/8.

In general, the special number is the current year minus 250/1.

So for 2009 it will be 1758/9. For 2049, it will be 1798/9.

I guess this email won’t be stopping any time soon.