26 lines
1.1 KiB
Text
26 lines
1.1 KiB
Text
A [[wp:Vampire_number|vampire number]] is a natural decimal number with an even number of digits, that can be factored into two integers.
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These two factors are called the ''fangs'', and must have the following properties:
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::* they each contain half the number of the decimal digits of the original number
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::* together they consist of exactly the same decimal digits as the original number
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::* at most one of them has a trailing zero
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An example of a vampire number and its fangs: <code> 1260 : (21, 60) </code>
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;Task:
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# Print the first '''25''' vampire numbers and their fangs.
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# Check if the following numbers are vampire numbers and, if so, print them and their fangs:
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<big><code> 16758243290880, 24959017348650, 14593825548650 </code></big>
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Note that a vampire number can have more than one pair of fangs.
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;See also:
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* [http://www.numberphile.com/videos/vampire_numbers.html numberphile.com].
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* [http://users.cybercity.dk/~dsl522332/math/vampires/ vampire search algorithm]
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* [[oeis:A014575|vampire numbers on OEIS]]
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<br><br>
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