title: Multiply all combinations of two lists
body: <p>I really want to know how to extract all the element from two lists and multiply each other. For example, if there are two lists</p>
  
  <pre><code>A=[1,3,5,7,9]
  B=[2,4,6,8]
  </code></pre>
  
  <p>I want to do 1X2, 1X4, 1X6, 1x8, 3x2... etc.
  One element from A X one element from B.
  I tried to use zip but because of length difference, I couldn't get right answers.</p>