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MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Your Age By Restaurant Math

This is doing the rounds:

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.

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!!!)

This will only work in 2007

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

Ma+th=fun

Member

Registered: 2007-05-08

Posts: 41

Re: Your Age By Restaurant Math

i got 310... which ( surprisingly ) had the correct number, 3. i dont understand the last part. do i add 10, or put 10 before/after my number?

It was way cool!

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I love pi.

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: Your Age By Restaurant Math

It means you are 10 ... right?

And if you don't want people to know your age I can edit it, or just pretend you got it wrong

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

pi man

Member

Registered: 2006-07-06

Posts: 251

Re: Your Age By Restaurant Math

1.  the number you pick is X
2.  multiply by 2:  2x
3.  Add 5:   2x + 5
4:  Multiply by 50:   100x + 250
5:  Add 1757 (you had your birthday this year):  100x+2007 (look familiar?)
6:  Subtract the year you were born (Y):  100x + (2007 - Y).

(2007 - Y):   The current year minus the year you were born = your age.   Since that is most likely a 2 digit number, when you add 100x you get a 3 digit number in the format XAA where X is the number you originally picked and AA is your age. 

And, yes, this will only work for this year but it wouldn't take much modification to get it to work for any other year.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Your Age By Restaurant Math

If Y is the current year, add Y−250 (had birthday) or Y−251 (not had birthday) in Step 5.

Steps 2–4 can be combined into just one: “Multiply that number by 100 and add 250.” I suppose the anonymous creator split it up into three steps just to make the process less obvious.

Last edited by JaneFairfax (2007-05-20 20:53:02)

Ma+th=fun

Member

Registered: 2007-05-08

Posts: 41

Re: Your Age By Restaurant Math

I dont mind people knowing my age so dont worry and i finally get it; the first number is the number of times you like to go out and the second is your age. nice puzzle. tks

Last edited by Ma+th=fun (2007-05-24 09:29:47)

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I love pi.

Daniel123

Member

Registered: 2007-05-23

Posts: 663

Re: Your Age By Restaurant Math

That ws really good! Why only in 2007 though?

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: Your Age By Restaurant Math

hehe it worked too

1 -> 116 -> 1, 16yrs

i love these sort of things, akes you go through loads of setps, but itll work no matter what

Last edited by luca-deltodesco (2007-05-24 10:13:27)

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The Beginning Of All Things To End.
The End Of All Things To Come.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Your Age By Restaurant Math

That ws really good! Why only in 2007 though?

According to pi man's conversion of the steps into algebra, your age is determined by (2007-Y), where Y is the year you were born. It's fairly easy to see why that works this year and why it won't work next year unless the steps are tweaked a bit.

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Why did the vector cross the road?
It wanted to be normal.

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Your Age By Restaurant Math

And I have already given the recipe for how to tweak it.

If Y is the current year, add Y−250 (had birthday) or Y−251 (not had birthday) in Step 5.

So for 2007, you add 1757 (had birthday) / 1756 (not had birthday) in Step 5. So if you want to keep on telling the joke next year, you would have to add 1758 / 1757 in the fifth step. Had you told the joke eight years ago (1999), Step 5 would have entailed adding 1749 / 1748. And if you are still telling the joke in twelve years’ time (2019), it will be 1769 / 1768.

Get it?

Daniel123

Member

Registered: 2007-05-23

Posts: 663

Re: Your Age By Restaurant Math

Yep!