title: Calculation returns NaN with dynamic values
body: <p>The following calculation works fine if I code the values by hand, but with dynamic values I always end up with NaN.</p>
  
  <pre><code>vals.tension = Math.round( ( Math.pow( ( vals.frequency * ( vals.stringLength * 10 ) * vals.diameter ), 2 ) * ( Math.PI * vals.density / 9810000000000 ) ) * 100 ) / 100;
  </code></pre>
  
  <p>If I add the following values it all works fine:</p>
  
  <pre><code>Math.round( ( Math.pow( ( 389.723 * ( 66 * 10 ) * .44 ), 2 ) * ( Math.PI * 1300 / 9810000000000 ) ) * 100 ) / 100;
  // 5.33
  </code></pre>
  
  <p>If I write out the values by hand it also works ok:</p>
  
  <pre><code>var vals = {
  frequency: 389.723,
  stringLength: 66,
  diameter: .44,
  density: 1300
  };
  </code></pre>
  
  <p>But if I try to dynamically re-create exactly the same values via user input I get NaN. I've checked the values via console.log and they are EXACTLY the same (they're not strings) and they all get added ok to the object, but the actual calculation when preformed dynamically (in Safari) returns NaN.</p>