Strange Sequence

Kids Learning

Strange Sequence

Here is a sequence of numbers:

1 11 21 1211 111221

It seems to be a strange sequence, but yet there is a system behind it…

The Question: What is the next term in this sequence?

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Solution

The system behind the sequence is that each number (except the first one of the sequence) “describes” the previous number. So 11 means one “1″, 21 means two times a “1″, 1211 means one “2″ and one “1″, and 111221 means one “1″, one “2″, and two times a “1″. The number following on 111221 is therefore 312211 (three times a “1″, two times a “2″, and one “1″).