Difference between revisions of "1999 AIME Problems/Problem 5"

 
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== Problem ==
 
== Problem ==
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For any positive integer <math>\displaystyle x_{}</math>, let <math>\displaystyle S(x)</math> be the sum of the digits of <math>\displaystyle x_{}</math>, and let <math>\displaystyle T(x)</math> be <math>\displaystyle |S(x+2)-S(x)|.</math>  For example, <math>\displaystyle T(199)=|S(201)-S(199)|=|3-19|=16.</math>  How many values <math>\displaystyle T(x)</math> do not exceed 1999?
  
 
== Solution ==
 
== Solution ==
  
 
== See also ==
 
== See also ==
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* [[1999_AIME_Problems/Problem_4|Previous Problem]]
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* [[1999_AIME_Problems/Problem_6|Next Problem]]
 
* [[1999 AIME Problems]]
 
* [[1999 AIME Problems]]

Revision as of 01:48, 22 January 2007

Problem

For any positive integer $\displaystyle x_{}$, let $\displaystyle S(x)$ be the sum of the digits of $\displaystyle x_{}$, and let $\displaystyle T(x)$ be $\displaystyle |S(x+2)-S(x)|.$ For example, $\displaystyle T(199)=|S(201)-S(199)|=|3-19|=16.$ How many values $\displaystyle T(x)$ do not exceed 1999?

Solution

See also