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 Vampire numbers (Posted on 2012-10-31)
A "vampire number" is an integer with 2n digits that is the product of two n-digit numbers — the fangs — whose digits, when combined, form a permutation of the original digits (thus, multiplicity counts).

The smallest vampire numbers are 1260 (= 21 × 60) and 1395 (= 15 × 93). Technical point: The fangs cannot each end in a 0. So 126000 is not a vampire number.

You might have missed it, but October 5, 2010, was a vampire day because 10 05 2010 is an 8-digit vampire number. It equals 2010 × 5001. When is the next vampire day?

 No Solution Yet Submitted by Danish Ahmed Khan Rating: 5.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 Solution (for no mandated format) Comment 3 of 3 |
As there are different date formats possible, the possible next Vampire Day could be February 25, 2018.
YYMMDD = 180225 is the product of the fangs 225 and 801.
 Posted by Dej Mar on 2012-11-01 01:31:13

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