title: How to do scalar multiply on data frame column
body: <p>I’m sure this one is sitting right in front of me but I can’t see it. I have a data frame, “a”, such that:</p>
  
  <pre><code>&gt;a
           Chars    Numbers
  This      A        15
  That      B        22
  Other     C        18
  </code></pre>
  
  <p>I simply want to multiply the Numbers column by a scalar, say b &lt;- 10, and keep the other parts of the data frame intact. (I would get 150, 220, 180 in the Numbers column of the result, but the same row/column headings and Chars column.)</p>
  
  <p>What does not work is a * b, trying to use apply, or a$Numbers * b.</p>