Can anyone explain this?

[DoingKermit]

I posted this in another thread but thought i would make a new one anyways.

Take the last two digits of the year that you were born and add it to the age that you will be THIS year and it should equal 111.

It will work as long as you were born between 1900 and 1999.

BUT WHY?!

 

[Dr_Sister]

sister came up with 110

 

[FastFourierT]

well everyone whos born on a certain year is the same age this year(disregarding whenever theyve already had a birthday this year or not), so everybody's age this year + last 2 digits of their birthyear adds up to the same number. It happens to be 111 this year.

next year its going to be 112

before 1990 ? no.

90 + 21 is 111

95 + 16 is 111

before 2000, yes.

 

[DoingKermit]

Were you born after 1999?

 

[FastFourierT]

I guess if you count 00 in 2000 as 100, since its followed by 99 anyway, it works for all ages after 1900.

Also if you set 1900 as 0, and simply make everything lower than that as negatives(1899 is -1) it will work for centenarians as well.

 

[Thebatman]

Were you born after 1999?

GREAT SCOTT!!! I think you've foiled sisters plans to perform dastardly deeds.

 

[alzabo]

f(X) = (2011-X)+(X-1900) = 111 for any whole number X (the year you were born).
next year, the number will change to 112...

 

[DoingKermit]

i see! Thanks alzabo! So Dr_Sister might have accidentally put in the wrong age or year to get 110?

 

[alzabo]

Perhaps she hasn't had her birthday yet this year. I got 110 as well 'till I realized that I was supposed to put one number higher for my age.
The funny thing is that this function still gives 111 even for negative numbers.

In a bit more detail, (2011-X) + (X-1900) = 2011 - 1900 + X - X = 2011 - 1900 = 111

 

[FastFourierT]

not to disrespect your function, what's the purpose of the variable(or variate rather, since X is capitalized) in it ?

f(X) = (2011 - X) + (X - 1900) = 2011 - 1900 + (X - X) = 2011 - 1900 = 111 <=> f(X) = 111

(-X + X) cancels each other out, and 2011 - 1900 is indeed 111.

It will give 111 not for just positive number X, negative X, but any X, including real and irrational.

Again no hostility meant, I am a little anal about those things, for my own understanding that is.

 

[DoingKermit]

I thought that too. You have to put in the age you are GOING to turn this year and if you already had your b-day you just put in the age you are.

That's weird about the negative numbers. I like it!