Q: What field is your onChange script monitoring? Instead of using a string to initialize your total, try this:

function onChange(control, oldValue, newValue, isLoading, isTemplate) {

        if (isLoading)

                  return;

        if (newValue == oldValue)

                  return;

        var xyz = 0;;

        var a=parseInt(g_form.getValue('u_estimated_claim_amount_s'));

        var b=parseInt(g_form.getValue('u_estimated_claim_amount_g'));

        var c=parseInt(g_form.getValue('u_estimated_claim_amount_c'));

        xyz =a + b + c;

        g_form.setValue('u_estimated_r',xyz);  

}