One of the questions that may be asked about our new year is whether 2013 is composite or prime -- that is, whether it does or does not have factors other than 1 and the number itself. A shortcut useful here is this test for divisibility by 3 (offered as a 5x5 square):
An integer is
divisible by
3 if and only
if the sum of its
digits is also.
And so, since 2 + 0 + 1 + 3 = 6 (which is divisible by 3), then 2013 is divisible by 3. Indeed, the prime factorization is 2013 = 3 x 11 x 61.
My email on this New Year's morning contained a gift -- "Digits" -- a poem that compares numbers with nature, from Virginia poet and dream specialist Joan Mazza; she has given me permission to post it here.
Digits by Joan Mazza
Showing posts with label 2013. Show all posts
Showing posts with label 2013. Show all posts
Tuesday, January 1, 2013
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