<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
<script>
var jQ = $.noConflict(true);
// version 1
jQ( document ).ready(function() {
// Set totalhours to read only
jQ('input[name="TotalHours"]').prop('readonly', true);
// add the class sum to all inputs that we want to add
jQ('input[name^="hourstotalwk"]').addClass( "sum" );
// on keyup check that the value isn't blank and it's numeric
jQ('input[name^="hourstotalwk"]').on('keyup', function() {

if (jQ(this).val()!="" || jQ.isNumeric(jQ(this).val())){
// if input value is good fire the function
calc_dues();
}
});

// This is the calculate function
function calc_dues() {

var sum = 0;

jQ('.sum').each(function(){

if(jQ.isNumeric(this.value)){

sum += parseFloat(this.value);

jQ('input[name="TotalHours"]').val(sum);

}
});
}
});
</script>