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We don't normally do this

Eddie Mair | 10:19 UK time, Thursday, 24 May 2007

because otherwise we could just fill the Blog with emails but look - we just tried this...or rather Jasper and Jeremy, our editor and deputy for the day just tried it, and it does work. We don't care how, we just marvel at it.

It was sent in by Andrew Willis. Thank you.


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


This is pretty neat


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.

N.B. you may need a pen & paper for two or three calculations.

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 1757 .....

If you haven't, add 1756.

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!!!!!)



  1. At 10:38 AM on 24 May 2007, Big Sister wrote:

    Oh, Eddie, I just LOVE these maths games. Yes, indeed, it does work.

    There's another one I know. But I won't email it to you. Promise!

  2. At 10:49 AM on 24 May 2007, witchiwoman wrote:

    Cool - I'm sure theres a very simple explanation but frankly I don't care and don't want to know! :)

  3. At 10:50 AM on 24 May 2007, Fiona wrote:

    Wow, it does work! How??

  4. At 10:53 AM on 24 May 2007, Val P wrote:

    Good grief - it works!

    Come on then you mathematical spoilsports out there, put down your six-sigma presentations and tell us how it works then?

  5. At 10:56 AM on 24 May 2007, Lee Vitout wrote:

    According to my calculations I'm 96! I'll try again.

  6. At 10:56 AM on 24 May 2007, Electric Dragon wrote:

    Why does this work? Well, anyone with a GCSE in Maths could tell you. Essentially what it's telling you is that your age is 2007 (or 6 if you've not yet had your birthday) minus your birth year. The rest of the maths is simply misdirection to exploit the way people get frightened or mystified by anything vaguely mathematical. It is true that THIS IS THE ONLY YEAR IT WILL EVER WORK - because next year, you have to replace 1756 and 1757 with 1757 and 1758 respectively.

    It reminds me of a verse from Lewis Carroll's Hunting of the Snark:

    "Taking Three as the subject to reason about—
    A convenient number to state—
    We add Seven, and Ten, and then multiply out
    By One Thousand diminished by Eight.

    "The result we proceed to divide, as you see,
    By Nine Hundred and Ninety and Two:
    Then subtract Seventeen, and the answer must be
    Exactly and perfectly true."

  7. At 11:13 AM on 24 May 2007, jonnie wrote:

    Wow -- Don't spoil it electric dragon :-(

    It's magic okay!

  8. At 11:26 AM on 24 May 2007, John H. wrote:

    Electric Dragon is rather more eloquent than me, but spot on. The "add 2 and multiply by 50" steps gives you a figure of as many hundreds as the number of times you said you wanted to eat out (i.e. 3 times = 300, 2 time = 200, etc) which then gives you the same number back at the end, and the "plus 5 and multiply by 50" give you the 250 you need to make up the difference between 2007 and 1757/6.

    If you're over a hundred, it doesn't work.

  9. At 11:37 AM on 24 May 2007, Abi Brady wrote:

    note the hidden encoding of 2007 in the steps. multiply by 2, add 5, multiply by 50, then add 1757. or, in other words, multiply by 100, and add 2007!

  10. At 11:40 AM on 24 May 2007, Tim wrote:

    Okay, so it works.

    But I must ask why I just wasted 3 minutes of my time reading and doing it?

    Hardly a revelation!

  11. At 12:06 PM on 24 May 2007, Fearless Fred wrote:

    Well, it was more fun that the TWO six sigma presentations I've just done!

  12. At 12:23 PM on 24 May 2007, Val P wrote:

    Two, was it Ffred? Hope they were dazzled by your brilliance, and realised whose company you had to sacrifice last night to get them polished!

  13. At 12:43 PM on 24 May 2007, Wonko wrote:

    There's another neat arithmatic trick you can do, which you can present as mind reading:

    Think of a number between 1 and 10.

    Multiply that number by 9

    If you have a two digit answer, add the two numbers together. E.g. if you have 45 as your answer, add 4 and 5.

    Now subtract 5 from your total.

    If you were to think of the alphabet being numbered, so a=1, b=2 through to z=26, take the number you now have and equate it to a letter of the alphabet.

    Now think of a country that begins with that letter.

    Then think of an animal that begins with the second letter of that country's name.

    Finally, think of the colour of that animal.

    There is a very good chance that you've just thought of a grey elephant from Denmark.

    The number you should have ended up with was four, and the letter was therefore D

  14. At 12:43 PM on 24 May 2007, Stewart M wrote:

    Don't care that its just a simple maths trick. its great fun! Of course I know how old I am so did not need to work it out

  15. At 12:47 PM on 24 May 2007, RJD wrote:

    Fearless - You should have done a twelve sigma presentation and got it over with!

  16. At 12:58 PM on 24 May 2007, Humph wrote:

    I could have told you that even though I do not have a GCSE in maths, E Dragon (6). I have a GCE O-Level! Well it was a thread about our age, wasn't it?


  17. At 01:17 PM on 24 May 2007, Otto's Mummy wrote:

    Wow - as I have a serious (and I mean serious) maths hangup, I struggled at point 2!!! But after finding the calculator I was spooked! Trouble is, I thought it would tell me the real number of times I'd like to eat out (once a month around here) and not the little fib I had to put in.

  18. At 01:20 PM on 24 May 2007, John H. wrote:

    Wonko, obviously heard that before. But it's only today that I've realised the that the "multiply by 9" step is always going to result in a number where adding the digits equals nine. Why's that then? And what numbers act in a similar way?

    Anyway, my black umbrella from Dubai was clearly wrong.

  19. At 01:34 PM on 24 May 2007, Chris Ghoti wrote:

    I thought the rule was meant to be that all arithmetical puzzles always came out with the answer 23, or some number that can be juggled to reach 23.

    Hail Eris! All Hail Discordia!

    (Well, it was all about our age, wasn't it?)

  20. At 02:27 PM on 24 May 2007, Wonko wrote:

    John H: You're quite correct, the multiply by nine part is the sneaky bit. It assures that you always get nine as the next part, so subtracting five will always give four, and so the letter will always be D. The only other option I have heard is a black and white ostrich from the Dominican Republic, so congratulations on being creative!

    ;o) []

  21. At 03:05 PM on 24 May 2007, Little Red wrote:

    John H at 18. Probably because Dubai is a city not a country...

    There aren't may D's. But we managed to get eel instead of elephant. But it was still grey and fom Denmark. So that's still spooky.

  22. At 03:06 PM on 24 May 2007, witchiwoman wrote:

    Along the lines of 'wouldn't normally do this' but this was so bizarre....and a little stomach churning


  23. At 03:53 PM on 24 May 2007, John H. wrote:

    Thanks Little Red - it's always good to be put right when you're spouting rubbish.

    How about Djibouti? And a big eye tunny? Ooo, they're grey too. Spooky!

  24. At 04:11 PM on 24 May 2007, Ed Iglehart wrote:

    Only for the snake.

  25. At 05:00 PM on 24 May 2007, DI Wyman wrote:

    ....nice one......seems that I am the same age as Gillian...:)

  26. At 05:10 PM on 24 May 2007, Gillian wrote:

    DIWy (25) Actually, I think you'll find I'm younger than you! ;o)

  27. At 05:28 PM on 24 May 2007, Sodom&Gomorrah wrote:

    sorry to disappoint. Black Jackdaw from Djibuti(?).

    Loved the test though, and yes the digits of all multiples of 9 below 10 add up to 9.

  28. At 05:35 PM on 24 May 2007, Val P wrote:

    ...and 11 months younger than I am!

  29. At 09:40 PM on 24 May 2007, madmary wrote:

    I don't care how it works, like jonnie said it's magical! I'm not telling anyone how many times I'd like to eat out though!


  30. At 11:13 PM on 24 May 2007, mittfh wrote:

    Anyone tried meddling with SQRT(-1) yet? The one aspect of A level Maths I could never get my head around was complex numbers. I'm sure they have their uses, but basing calculations on numbers that even mathematicians call "Imaginary" completely threw me.

    As for number games, my favourite involves no calculations at all - just logic. Take a 9x9 square, and fill it in so that each row, column and 3x3 block contains the digits 1 to 9.

  31. At 09:45 AM on 25 May 2007, Big Sister wrote:

    mittfh: Hm. Another Sudoku fan/addict, I see.

    Mind you, the last couple of weeks I've been struggling a bit with the fiendish. Could my brain be finally frying [too much frogging, I hear you say ....]

  32. At 11:12 AM on 25 May 2007, Wonko wrote:

    S&G: Well, that's a new one! 12/10 for creativity! Well done. ;o) []

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