We Got A Problem #9: Yearly Multiplication

This Saturday (December 1, 2012) gets written as a short date as 12/1/12 (or, outside the US, generally 1/12/12).  Either way, it’s interesting because 12 x 1 = 12.  That’s happened a lot this year, including June 2.

1. How many times in a century will this happen? It happened once in 2001, twice in 2002.

2. In what year(s) will this happen the most times?  Are there years when it won’t happen?

3. Days like 12/12/44 or 8/25/00 sort of work: 12 x 12 = 144, which you’d write as 44 in a two-digit year.  If you include these days too, how many times in a century does it happen?  Cooool.

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About Bowen Kerins
Bowen is a mathematics curriculum writer. He is a lead author of CME Project, a high school curriculum focused on mathematical habits of mind. Bowen leads professional development nationally, primarily on how math content can be taught with a focus on higher-level goals. Bowen is also a champion pinball player and once won $1,000 for knowing the number of degrees in a right angle.

One Response to We Got A Problem #9: Yearly Multiplication

  1. Dan Goldner says:

    Hah! That is cool — esp. #3 🙂

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