i mean for the code above (http://forums.asp.net/post/4843467.aspx) without javascript, i leave the option 0 (<option value="0">Select</option>).

So, i want to add a ModelState.AddError for this option, if the user leave option 0.

Its something like this example but is not as AsInt, is as AsDecmial

if (Request["employees"].IsInt()) {
            employeecount = Request["employees"].AsInt();
        } else {
            errors = true;
            @:Employee count must be a number.<br />
        }