Difference between revisions of "Overcounting"

 
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== Description ==
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Strategic '''overcounting''' is the process of counting more than desired and then systematically "correcting" for overcounted elements by removing them from the total count via subtraction or division. The idea of strategic overcounting is fundamental to [[combinatorics]] and plays a role in incredibly important counting tools such as [[combinations]] and the [[Principle of Inclusion-Exclusion]].
Overcounting is the process of counting more than what you need and then systematically subtracting the parts which do not belong.
 
  
== Example ==
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==Related Videos==
Let S be the set of all rational numbers <math>{r}</math>, <math>0 < r < 1</math>, that have a repeating decimal expansion in the form <math>0.abcabcabc\dots</math>, where the digits a, b, and c are not necessarily distinct.  To write the elements of S as fractions in lowest terms, how many numerators are required?
 
  
''(Solution Coming)''
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* [http://www.artofproblemsolving.com/Videos/external.php?video_id=59 (Counting the Number of Arrangements of Letters in a Word)]
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* [http://www.artofproblemsolving.com/Videos/external.php?video_id=60 (Counting pairs)]
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* [http://www.artofproblemsolving.com/Videos/external.php?video_id=57 (Counting Objects in a Circle Part 1)]
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* [http://www.artofproblemsolving.com/Videos/external.php?video_id=61 (Counting Objects in a Circle Part 2)]
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== More Examples ==
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* [[2004 AIME I Problems/Problem 3|AIME 2004I/3]]
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==Introductory Problems==
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*How many different words can be formed with the letters <math>AAAABBCCDDDPPP</math>?(Not necessarily meaningful words)
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== See also ==
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* [[Casework]]
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* [[Complementary counting]]
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* [[Constructive counting]]
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{{stub}}
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[[Category:Definition]]
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[[Category:Combinatorics]]

Latest revision as of 22:23, 22 July 2025

Strategic overcounting is the process of counting more than desired and then systematically "correcting" for overcounted elements by removing them from the total count via subtraction or division. The idea of strategic overcounting is fundamental to combinatorics and plays a role in incredibly important counting tools such as combinations and the Principle of Inclusion-Exclusion.

Related Videos

More Examples

Introductory Problems

  • How many different words can be formed with the letters $AAAABBCCDDDPPP$?(Not necessarily meaningful words)

See also

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