Question

Edit: Solution: http://jsfiddle.net/VnXtP/

Why dosent this work?
http://jsfiddle.net/uc7kT/

<input type="text" name="item_quantity" id="item_quantity" value="1" />
<input type="text" name="item_price" id="item_price" value="24998" hidden="hidden" />

$('#item_quantity').change(function() {
    var quantity = $('#item_quantity').val();
    var price = $('#item_price').val();
    var total =  quantity * price;

    alert(total.length);
});

Answer 1

Length is defined for strings, not numbers. If you wish to do this as a mathematical operation, you must convert the input strings to numbers first. If you actually want the length of the number string (I don’t know why you would), you need to convert the number to a string first:

$('#item_quantity').change(function() {
    var quantity = parseInt($('#item_quantity').val(), 10);
    var price = parseFloat($('#item_price').val());
    var total =  quantity * price;

    alert(total.toString().length);
});