why does this work?

Question

A little quiz that will predict your age.


It takes less than a minute. Work this out as you read. Don't cheat by scrolling down to the end.

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 IS THE ONLY YEAR (2007) IT WILL EVER WORK, SO SPREAD IT AROUND WHILE IT LASTS

Answer 1

The answer follows from elementary algebra.

A. Let 't' be the number of times you want to eat per week, take 1757 of those two choices (so that you've had your birthday this year), and let your age now be 'a', so that the year in which you were born would be (2007 - a).

Then your successive steps lead to a final result of

(2t + 5)*50 + 1757 - (2007 - a)

= 100t + (250 + 1757) - 2007 + a.

But (250 + 1757) = 2007, so that your final result is in fact:

100t + a.

Then, PROVIDED that your age is LESS THAN 100 (a condition that you FORGOT to stipulate!), as 't' was less than 10, the first DIGIT ### will indeed be 't', and the remaining two digits will give your age.

B. What about the choice between 1757 and 1756? :

If you haven't yet had your birthday in 2007, then your birth year is (2006 - a), where a is your "current age" in years (which was established LAST YEAR). Because of the replacement of 2007 by 2006, the 1757 must itself be replaced by 1756, in order to still arrive at the final result of 100t + a.

Live long and prosper.

### NOTE: Your TWO conditions on the number of times you go out to eat are too restrictive. There is really NO UPPER LIMIT ( other than your desired waistline) on how often you go out to eat, or on the number of digits in the final answer to three. Simply ignore the last two digits of any final result, and the remaining number (no matter how many digits long it is) will still equal your initial input for 't'.

Similarly, why stipulate that you want to go out to eat "more than once" per week? It will work fine for eating out once. I think you may have meant "at least once."

Answer 2

ok: note that the difference between 2007 and 1757 is 250. So adding 1757 and then subtracting a birth year simply cancels out the 250 less your age from steps 3 and 4. Steps 2 and 4 tok the original number and mutiplied it by 100, so is in the hundreds place of the final answer.

the number in step 5 will be 1758 next year.

Answer 3

It doesn't work for anyone who has already turned 100 or more.

To make it work for 2008, simply add 1 to both of the numbers 1757 and 1756 (i.e. 1758 and 1757).

Add one the these numbers each year after that.

This is what you call an algorithm.
Internally it knows the key number is 2006, but its hidden by
the dinner*2+5 part.

In other words:

1. I you have already had you birthday this year your number is 1, otherwise your number is 0.
2. Add 2006 to your number.
3. Subtract the year of your birth.
Presto the answer is your age.

Answer 4

You wind up with 100x + 2007, where x is the number you picked in step 1. So when you subtract the year you were born you get your two digit age and he hubdreds digit will be x.

The trick only works for people <100.

Answer 5

Number of days you like to go out to eat = x
Year you were born = y

1. x
2. 2x
3. 2x+5
4. 50(2x+5) = 100x +250
5. 100x+250 + 1757 = 100x + 2007
6. 100x + (2007-y)
100x is the first number moved over to the hundreds place, 2007-y is the number of years you've been alive.

Note: it doesn't work if you are over 100.

Answer 6

smarty smart but still mathmetics :)

next year 2008 will work if you add in step 5 1758
2009 add 1759
2010 add 1760
soo on....

regards,

Answer 7

50(2x+5)[phone]+myage = 100x+250-250+myage =
100x+myage

Answer 8

Your " number of times you go out to eat" was just something to confuse the gullible ones. But you asked me about my birthdate, so that's it. P.S. I figured this out in less than a second, for your info.

Answer 9

It works this year because someone figured out the algorithm to make it work.

Answer 10

It's math. You can make an equation for this and see how it works.