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View Full Version : A nice mathematical challange 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 |