title: Count items in Dictionary that begin with certain text
body: <p>I have a dictionary that looks something like this</p>
  
  <p>test1 : 123<br/>
  test2 : 456<br>
  another1 : abc<br>
  test3 : 789<br>
  another2 : def<br></p>
  
  <p>How can I get a count of all the items that begin with "test" in c# framework 3.5?</p>