"how to change calculation when the row is removed from a table" Code Answer

     $(document).on('change', 'tr td:nth-child(6), tr td:nth-child(5), tr td:nth-child(4)', .
            'remove3'
            function() {
                var total = 0;
                var sqty = 0;
                var tr = $(this).parent();
                var qty = tr.find('td:nth-child(4)').find('input').val();
                var rate = tr.find('td:nth-child(5)').find('input').val();
                var amount = qty * rate;
                tr.find('td:nth-child(6)').find('input').val(amount);

                var tbody = tr.parent();

                $(tbody).find('tr').each(function() {
                    total += number($(this).find('td:nth-child(6)').find('input').val());
                    sqty += number($(this).find('td:nth-child(4)').find('input').val());
                });

                $('#tietotal').val(total);
                $('#sqty').val(sqty);
                $('#grandtot').val(total);
            })

    script to create a next row automatically:

        $('.tb3').on('keydown', 'input', function(e) {
            var keycode = e.keycode;
            if (keycode !== 9) return;
            var $this = $(this),
                $lasttr = $('tr:last', $('.tb3')),
                $lasttd = $('td:last', $lasttr);
            if (($(e.target).closest('td')).is($lasttd)) {
                var cloned = $lasttr.clone();
                cloned.find('input').val('');

                $lasttr.after(cloned);
            }
        });

    script to delete row:

        $(document).on('click', '.remove3', function() {
            var trindex = $(this).closest("tr").index();
            if (trindex > 0) {
                $(this).closest("tr").remove();
 $('.qty').trigger('change');
            } else {
                alert("sorry!! can't remove first row!");
            }
        });