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What do these numbers have in common that no other numbers between 1 and 100 share? 4, 6, 12, 30, 33, 36, 40, 45, 50, 54, 56, 60, 70, 81, 88, 90, 100

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They are all on the list of numbers in your post. – Zev Chonoles Oct 13 '11 at 23:38
Good one! Anything else? – Josie Oct 13 '11 at 23:40
oeis.org/A092320 – Chris Taylor Oct 13 '11 at 23:40
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This? – J. M. Oct 13 '11 at 23:41
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"American English" is to help decide whether the next term is "one hundred and eight" or "one hundred twelve". – Henry Oct 14 '11 at 0:10
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Each of the numbers $n$ in your list is divisible by the number of digits in the English word for $n$.

For example:

  • the English word for '4' is "four" which has 4 letters, and 4 / 4 = 1
  • the English word for '6 is "six" which has 3 letters, and 6 / 3 = 2
  • the English word for '12' is "twelve" which has 6 letters, and 12 / 6 = 2
  • the English word for '30' is "thirty" which has 6 letters, and 30 / 6 = 5
  • the English word for '33' is "thirty-three' which has 11 letters, and 33 / 11 = 3

Do you see the pattern now?

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Yes! Thanks so much. – Josie Oct 13 '11 at 23:51

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