A nice mathematical challange [Archive]

Omri

10-09-06, 07:31 AM

Hello,

A friend gave me this challange - there is a given series:
1, 11, 21, 1211, 1231, 131221...
What is the next number?

It's probably one of those tricky questions, I just can't figure out the trick in it...

Thanks :)

Absane

10-09-06, 10:06 AM

11131112211

Absane

10-09-06, 10:51 AM

Though I think you made a typo in the puzzle after 1211.

Absane

10-09-06, 10:52 AM

1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, ...

Omri

10-09-06, 12:53 PM

I checked and there's no typo. But I don't really understand how you got to this solution.

Absane

10-09-06, 12:56 PM

1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, ...

Start with 1.

There is one 1.. so 11.

For 11, there are two 1's.. so 21.

For 21, there is one 2 and one 1.. so 1211

1211: one 1, one 2, two 1.. so 111221.

Keep going.

Absane

10-09-06, 12:58 PM

Your sequence starts out just like this.. then it seems to go off into something unknown.

geodesic

10-09-06, 01:34 PM

I've seen this puzzle before, and I can say that Omri is correct, no typo. You're almost there Absane.

leopold99

10-09-06, 02:29 PM

Hello,

A friend gave me this challange - there is a given series:
1, 11, 21, 1211, 1231, 131221...
What is the next number?

It's probably one of those tricky questions, I just can't figure out the trick in it...

Thanks :)
132231

spuriousmonkey

10-09-06, 02:49 PM

I've seen this puzzle before, and I can say that Omri is correct, no typo.

Except in the title.

draqon

10-09-06, 02:58 PM

Hello,

A friend gave me this challange - there is a given series:
1, 11, 21, 1211, 1231, 131221...
What is the next number?

It's probably one of those tricky questions, I just can't figure out the trick in it...

Thanks :)

1, 11, 21, 1211, 1231, 131221, 132231, 232221, 134211, 14131231, 14231241, 24132231

geodesic

10-09-06, 03:50 PM

Congrats, Leo.
Draqon, you're just showing off!

Absane

10-10-06, 12:53 AM

Hello,

A friend gave me this challange - there is a given series:
1, 11, 21, 1211, 1231, 131221...
What is the next number?

It's probably one of those tricky questions, I just can't figure out the trick in it...

Thanks :)

Oh I see it.

Bastard trying to trick me.

Omri

10-10-06, 08:30 AM

I realise you solved it, but, you see, just giving me the solution is really nice but it would be great if you explained how you solved. I don't really understand how you got these answers.

Thanks!

Pete

10-10-06, 08:37 AM

The last number in the given sequence is 131221.
That number contains 1 3, 2 2s, and 3 1s. So the next number is 132231.

Sputnik

10-11-06, 05:04 AM

1= one one = 11
11= two one(s) = 21
21 = one two, one one = 1211
1211 = one two , three one(s) = 1231
1231 = one three , one two, two one(s) = 131221
131221 = one three, two two(s), three one(s) = 132231