title: Get the Mantissa of a Java BigDecimal
body: <p>I want to do some simple math with some very small and very large numbers. I figured I'd start with BigDecimal:</p>
  
  <pre><code>scala&gt; java.math.BigDecimal.valueOf(54, 45) 
  res0: java.math.BigDecimal = 5.4E-44
  </code></pre>
  
  <p>How do I then get the the mantissa? Either <code>54</code> or <code>5.4</code> would be fine.</p>