Difference between revisions of "2013 UNCO Math Contest II Problems/Problem 8"

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== Solution ==
 
== Solution ==
 
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(a) <math>998,910</math> (b) <math>4,020</math>
  
 
== See Also ==
 
== See Also ==

Latest revision as of 02:29, 13 January 2019

Problem

EXAMPLE: The non-terminating periodic decimal $0.124124 \ldots = 0.\overline{124}$ has period three and is abbreviated by placing a bar over the shortest repeating block.

(a) If all digits $0$ through $9$ are allowed, how many distinct periodic decimals $0.\overline{d_1d_2 \ldots d_6}$ have period exactly six? Do not include patterns like $0.323$ and $0.17$ that have shorter periods.

(b) If only digits $0$ and $1$ are allowed, how many distinct periodic decimals $0.\overline{d_1d_2\ldots d_{12}}$ have period exactly $12$?


Solution

(a) $998,910$ (b) $4,020$

See Also

2013 UNCO Math Contest II (ProblemsAnswer KeyResources)
Preceded by
Problem 7
Followed by
Problem 9
1 2 3 4 5 6 7 8 9 10
All UNCO Math Contest Problems and Solutions