Difference between revisions of "2011 UNCO Math Contest II Problems/Problem 2"

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As an example, <math>20</math> <math>\underline{can}</math> be so expressed since <math>20 = 2 + 6 + 2\cdot 6</math>.
 
As an example, <math>20</math> <math>\underline{can}</math> be so expressed since <math>20 = 2 + 6 + 2\cdot 6</math>.
 
== Solution ==
 
== Solution ==
 
+
<math>\{22,28,30\}</math>
  
 
== See Also ==
 
== See Also ==

Latest revision as of 03:20, 13 January 2019

Problem

Let $m$ and $n$ be positive integers. List all the integers in the set $\left\{ 20 ,21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31\right\}$ that $\underline{cannot}$ be written in the form $m+n+m \cdot n$. As an example, $20$ $\underline{can}$ be so expressed since $20 = 2 + 6 + 2\cdot 6$.

Solution

$\{22,28,30\}$

See Also

2011 UNCO Math Contest II (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
1 2 3 4 5 6 7 8 9 10
All UNCO Math Contest Problems and Solutions