multiplication error
<p>If I multiply 12 x 25.4 i get 304.7 whereas I expect 304.8.  I see that using odd numbers x 25.4 I get the correct answers but using even numbers always seem to be off by 0.1.  I am writing a scientific app that is heavily based on formulas so any insight would be helpful. </p>

<pre><code>if (((m1_sqs1_spinner.getSelectedItem().toString().equals("in"))))  

    { // start square in inches
         double m1_sqs1_eng = new Double(m1_sqs1.getText().toString()); 

         double square_effective_dia_inch = m1_sqs1_eng;

         double square_effective_dia_mm = square_effective_dia_inch * 25.4;
         m1_ed_mm.setText(Double.toString(square_effective_dia_mm));

    } // end square in inches
</code></pre>
