View source for 2011 UNCO Math Contest II Problems/Problem 2

== Problem ==

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


== See Also ==
{{UNCO Math Contest box|n=II|year=2011|num-b=1|num-a=3}}

[[Category:Introductory Algebra Problems]]