13112221 - Number sequence - 1113213211

Here is a sequence. What is the next number?

8

8,000,000,000

8,000,000,008

8,000,000,800

The hint was to say the numbers aloud. This hints that it is the words describing the numbers rather than their value or symbol that is important. If you look at 1, 2, 3, 4, 5, 6, 7, 8, 9, then the obvious order is their value, but if you look at one, two, three, four, five, six, seven, eight, nine, then it might occur to you to put them in alphabetical order. This would start with 'eight'. In fact, if you ordered all whole numbers in alphabetical order of name, 'eight' would still be first, followed by eight billion, then eight billion and eight, eight billion eight hindred, and the next one: eight billion eight hindred and eight. (Told you that it was cheating!)

You might get annoyed at this, but it does teach you that you can look at numbers in different ways. A number has both a value, a symbol and a name.

This is an infinitely long series. It has an interesting property: although the series is infinite, you know its last element: zero!