121, 111211, 311221 Puzzle (Look and Say Sequence)Date: 10/23/2001 at 18:53:18 From: Joey Subject: What's the next number? 121, 111211, 311221 - what's the next number? Date: 10/23/2001 at 22:28:06 From: Doctor Paul Subject: Re: What's the next number? The first number is 121. If you were to describe this number to someone who was writing it down digit by digit, you would say: Write down a single one - that is, one one. Then write down a single two - that is, one two. Finally, write down a single one - that is, one one. Put them together: one one one two one one Notice that this gives the next number: 111211 To describe this number in words digit by digit gives: three ones, one two, two ones = 311221 A similar pattern shows that the next numbers in the sequence are: 13212211, 111312112221, 31131112213211 - Doctor Paul, The Math Forum http://mathforum.org/dr.math/ |
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