how to sum values of selected options using jquery?

Question

I have 3 selectors, all selectors have some options with some values.

How do I sum all values of selected options?

<select name='anch1'>
    <option value='10'>10 ++</option>
    <option value='20'>20 ++</option>
    <option value='30'>30 ++</option>
    <option value='40'>40 ++</option>
    <option value='50'>50 ++</option>
</select>

<select name='anch2'>
    <option value='10'>10 ++</option>
    <option value='20'>20 ++</option>
    <option value='30'>30 ++</option>
    <option value='40'>40 ++</option>
    <option value='50'>50 ++</option>
</select>
    
<select name='anch3'>
    <option value='10'>10 ++</option>
    <option value='20'>20 ++</option>
    <option value='30'>30 ++</option>
    <option value='40'>40 ++</option>
    <option value='50'>50 ++</option>
</select>
    
<div>SUM OF SELECTED OPTIONS</div>

Answer 1

$('select').change(function(){
    var sum = 0;
    $('select :selected').each(function() {
        sum += Number($(this).val());
    });
     $("#sum").html(sum);
});

http://jsfiddle.net/8mnQR/1/