Difference between revisions of "Complementary counting"

(Introductory)
(Introductory)
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=== Introductory ===
 
=== Introductory ===
 
* [[2006_AMC_10A_Problems/Problem_21 | 2006 AMC 10A Problem 21]]
 
* [[2006_AMC_10A_Problems/Problem_21 | 2006 AMC 10A Problem 21]]
* [[2002 AIME I Problems/Problem 1| 2002 AIME I Problem 1]]
+
* [[2002 AIME I Problems/Problem 1 | 2002 AIME I Problem 1]]
 +
* [[2008 AMC 12B Problems/Problem 22 | 2008 AMC 12B Problem 22]]
  
 
=== See also ===
 
=== See also ===

Revision as of 16:51, 10 August 2010

Complementary counting is counting the complement of the set we want to count, and subtracting that from the total number of possibilities, or the universal set for that particular problem. A big hint that complementary counting may lead to a quick solution is the phrase "at least".


Examples

Introductory

See also

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