Expert: Sherry Wallin - 11/23/2008

Question
Explain the sequence and what is the next number?
1,11,21,1211,111221.... this is on 6th grade homework...that I have been looking at for three days....please help me.....thankyou thankyou!!-Frustrated Mom

Answer
   *  Find the next number in the following sequence: 1, 11, 21, 1211, 111221,....

     This looks like a "math" sequence, but it isn't really. Instead, each term is a description of the preceding term. The first term is just one "1": 11. The second term is two "1's": 21. And so forth:

           one 1: 11
           two 1's: 21
           one 2 and one 1: 1211
           one 1, one 2, and two 1's: 111221
           three 1's, two 2's, and one 1: 312211

     So the next term is "312211".
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