title: How does Delphi calculate TDateTime as a Float value?
body: <p>I am new in <code>Delphi</code> programming.
  While going through the <code>Data Types</code> in <code>Delphi</code> I found <code>TDateTime</code>.</p>
  
  <p>While using it in my test application I come to know that the <code>TDateTime</code> Object provide me a <code>Float\Double</code> value.</p>
  
  <p>I am little curious about <code>TDateTime</code> How it calculate the <code>Date Time</code> to <code>Double</code> value.</p>
  
  <p>Below is the example code which I had used:</p>
  
  <pre><code>var
    LDateTime: TDateTime;
    LFloat: Double;
  begin
     LDateTime := now;// current DateTime
     LFloat:= LDateTime; // provide me a float value   
  end;
  </code></pre>
  
  <p>Is it using any formula to calculate <code>Date and Time Value</code> from Windows?</p>
  
  <p>Can anyone suggest/provide me for some more information about working of <code>TDateTime</code>?</p>
  
  <p>Thanks in advance.</p>