title: Replacing if the first number is a zero and the number is greater than 2 places
body: <p>I have a calculator I'm working on and came across a problem. To combat so that users can't leave a field blank, I'm forcing a zero if the field is left empty. That's all fine, but the problem is that when the text in the field is deleted to remove the zero and enter a new number, it automatically enters zero so my new number looks like this: 05</p>
  
  <p>How do i run a replace where if there is more than 2 places in the number and the first number is zero, replace the zero? Here's the code i'm using for my calculator.</p>
  
  <pre><code>$(function(){
  
    calculate();
  
  $('.input').keypress(function (e) {
       //if the letter is not digit then display error and don't type anything
       if (e.which != 8 &amp;&amp; e.which != 0 &amp;&amp; (e.which &lt; 48 || e.which &gt; 57)) {
                 return false;
      }
     });
  
    $('.input').on('keyup',function(){
      if($(this).val()==''){
        $(this).val('0');
      }
      calculate();
    });
  
  });
  
  function calculate(){
  
    var d6 = parseFloat(($('#d6').val()).replace(/,/g,''));
    var d20 = parseFloat(($('#d20').val()).replace(/,/g,''));
    var b20 = d6;
    var e20 = parseFloat(($('#e20').val()).replace(/,/g,''));
  
    var f20 = d20*e20;
    var f22 = b20/f20;
    var f23 = (52-f22)*f20;
  
    $('#f20').html(formatCurrency(f20));
    $('#f22').html(f22.toFixed(2));
    $('#f23').html(formatCurrency(f23));
  
  }
  
  function formatCurrency(x) {
      return '$'+x.toString().replace(/\B(?=(?:\d{3})+(?!\d))/g, ",");
  }
  </code></pre>