title: How to multiply price by quantity and display price in text field?
body: <p>I'm trying to set up an order form for clothing.  The price of the item varies based on it's size.  I need it to multiply the value of the options in the size field (the price) by the quantity, and then display the total price.  I'm guessing there's some pretty simple script to make this happen but I'm a total newbie.</p>
  
  <p>I tried tinkering around with this script I found on here.  Is there something I can just add to this to make it work?:</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
  
  $(window).load(function(){
      $('form').change(function() {
      var total = 0;
      $.each($(".summable") ,function() {
          total += parseFloat($(this).val());
      });
      $("#sum").val(total)
      });
  });
      &lt;/script&gt;
  </code></pre>
  
  <p>Here's the form:</p>
  
  <pre><code>&lt;form&gt;&lt;br /&gt;Shirts:
  &lt;br&gt;Size&lt;br&gt;
  
                    &lt;select class="summable" name="shirt size" id="shirt size"&gt;
                      &lt;option value="0" selected="selected"&gt;Click to select&lt;/option&gt;
                      &lt;option value="20.00"&gt;Child(s) XSmall&lt;/option&gt;
                      &lt;option value="20.00"&gt;Child(s) Small&lt;/option&gt;
                      &lt;option value="20.00"&gt;Child(s) Medium&lt;/option&gt;
                      &lt;option value="20.00"&gt;Child(s) Large&lt;/option&gt;
                      &lt;option value="20.00"&gt;Child(s) Xlarge&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult XSmall&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult Small&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult Meduim&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult Large&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult XLarge&lt;/option&gt;
                      &lt;option value="21.00"&gt;Adult XXLarge&lt;/option&gt;
                    &lt;/select&gt;
  &lt;br /&gt;Quantity&lt;br&gt;
  
                    &lt;select name="shirt quantity" id="shirt quantity"&gt;
                      &lt;option  value="0" selected="selected"&gt;0&lt;/option&gt;
                      &lt;option value="1"&gt;1&lt;/option&gt;
                      &lt;option value="2"&gt;2&lt;/option&gt;
                      &lt;option value="3"&gt;3&lt;/option&gt;
                      &lt;option value="4"&gt;4&lt;/option&gt;
                      &lt;option value="5"&gt;5&lt;/option&gt;
                      &lt;option value="6"&gt;6&lt;/option&gt;
                      &lt;option value="7"&gt;7&lt;/option&gt;
                      &lt;option value="8"&gt;8&lt;/option&gt;
                      &lt;option value="9"&gt;9&lt;/option&gt;
                      &lt;option value="10"&gt;10&lt;/option&gt;
                    &lt;/select&gt;
  &lt;br&gt;
  &lt;br&gt;
  &lt;br /&gt;Jackets:
  &lt;br&gt;Size&lt;br&gt;
  
                    &lt;select class="summable" name="jacket size" id="jacket size"&gt;
                      &lt;option value="0" selected="selected"&gt;Click to select&lt;/option&gt;
                      &lt;option value="40.00"&gt;Child(s) XSmall&lt;/option&gt;
                      &lt;option value="40.00"&gt;Child(s) Small&lt;/option&gt;
                      &lt;option value="40.00"&gt;Child(s) Medium&lt;/option&gt;
                      &lt;option value="40.00"&gt;Child(s) Large&lt;/option&gt;
                      &lt;option value="40.00"&gt;Child(s) Xlarge&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult XSmall&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult Small&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult Meduim&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult Large&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult XLarge&lt;/option&gt;
                      &lt;option value="44.00"&gt;Adult XXLarge&lt;/option&gt;
                    &lt;/select&gt;
  &lt;br /&gt;Quantity&lt;br&gt;
  
                    &lt;select name="jacket quantity" id="jacket quantity"&gt;
                      &lt;option  value="0" selected="selected"&gt;0&lt;/option&gt;
                      &lt;option value="1"&gt;1&lt;/option&gt;
                      &lt;option value="2"&gt;2&lt;/option&gt;
                      &lt;option value="3"&gt;3&lt;/option&gt;
                      &lt;option value="4"&gt;4&lt;/option&gt;
                      &lt;option value="5"&gt;5&lt;/option&gt;
                      &lt;option value="6"&gt;6&lt;/option&gt;
                      &lt;option value="7"&gt;7&lt;/option&gt;
                      &lt;option value="8"&gt;8&lt;/option&gt;
                      &lt;option value="9"&gt;9&lt;/option&gt;
                      &lt;option value="10"&gt;10&lt;/option&gt;
                    &lt;/select&gt;
  &lt;br&gt;
  &lt;br&gt;
  
  
  Total:&lt;input id="sum" type="text"/&gt;
  
  &lt;/form&gt;
  </code></pre>
  
  <p>Any insight greatly appreciated, thanks.</p>