Difference between revisions of "2008 AMC 10A Problems/Problem 3"

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==Problem==
 
==Problem==
For the positive integer <math>n</math>, let <math><n></math> denote the sum of all the positive divisors of <math>n</math> with the exception of <math>n</math> itself. For example, <math><4></math> and <math><12>=1+2+3+4+6=16</math>. What is <math><<<6>>></math>?
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For the positive integer <math>n</math>, let <math><n></math> denote the sum of all the positive divisors of <math>n</math> with the exception of <math>n</math> itself. For example, <math><4>=1+2=3</math> and <math><12>=1+2+3+4+6=16</math>. What is <math><<<6>>></math>?
  
 
<math>\mathrm{(A)}\ 6\qquad\mathrm{(B)}\ 12\qquad\mathrm{(C)}\ 24\qquad\mathrm{(D)}\ 32\qquad\mathrm{(E)}\ 36</math>
 
<math>\mathrm{(A)}\ 6\qquad\mathrm{(B)}\ 12\qquad\mathrm{(C)}\ 24\qquad\mathrm{(D)}\ 32\qquad\mathrm{(E)}\ 36</math>

Revision as of 21:07, 13 October 2008

Problem

For the positive integer $n$, let $<n>$ denote the sum of all the positive divisors of $n$ with the exception of $n$ itself. For example, $<4>=1+2=3$ and $<12>=1+2+3+4+6=16$. What is $<<<6>>>$?

$\mathrm{(A)}\ 6\qquad\mathrm{(B)}\ 12\qquad\mathrm{(C)}\ 24\qquad\mathrm{(D)}\ 32\qquad\mathrm{(E)}\ 36$

Solution

$<<<6>>>\ =\ <<6>>\ =\ <6>\ =\ 6\quad\Longrightarrow\quad\mathrm{(A)}$

See also

2008 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 2
Followed by
Problem 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 10 Problems and Solutions