title: Swift - Multiply two NSDecimal Numbers
body: <p>I am currently attempting to multiply two <code>NSDecimal</code> Numbers, is this possible in <strong>Swift</strong>?</p>
  
  <p>I found the method '<code>decimalNumberByMultiplyingBy</code>' on the Apple Dev pages but I have used it as below and I am receiving a '<strong>Bad access</strong>' error.</p>
  
  <p>Purchase Price and Quantity are both <code>NSDecimalNumbers</code> in the Item class and are definitely populated (with purchase price of 35.99 and quantity of 30)</p>
  
  <pre><code>var one = item.purchasePrice
  var two = item.quantity
  
  let three: NSDecimalNumber = one.decimalNumberByMultiplyingBy(two)
  </code></pre>
  
  <p>I have tried it multiple ways but all the tutorials seem to be for Objective C.</p>
  
  <p>Thanks.</p>