Long calculation

Long calculation

I want to create long calculation form. What I mean?

I have 2 text box (num1 and num2) for enter number,  button (btnCalc1) for calculation and text box (res2) for result.

    <form name="calculus" action="">
        <input type='text' name='num1' id='num1' />
        <input type='text' name='num2' id='num2' />
        <input type='button' name='btnCalc1' value='Calc' />
        <input type='text' name='res2' />
    </form>

After I click button which calculate sum of numbers and show it in result text box. Also I create text box (num3) for enter number, 1 text box (res3) for result and 1 button (btnCalc2) for next calculation.

            var btnNum = 2;
            var txtNum = 3;

            $('#btnCalc1').click(function() {
                var iNum1 = eval($("#num1").val());
                var iNum2 = eval($("#num2").val());
                var iAns = iNum1 + iNum2;
                $("input[name='res2']").val(iAns.toString());

                var newText = "<br /><input name='num"+txtNum+"' type='text' />";
                var newBtn = "&nbsp;&nbsp;<input type='button' name='btnCalc"+btnNum+"' value='Calc' />";
                var newRes = "&nbsp;&nbsp;<input name='res"+txtNum+"' type='text' />";

                $("form[name='calculus']").append(newText);
                $("form[name='calculus']").append(newBtn);
                $("form[name='calculus']").append(newRes);

            });

My aim to write function which will cycle this process. I did like this but it not work.

$("input[name='btnCalc"+btnNum+"']").bind('click',{id: btnNum}, function(event) {
                var iNum1 = eval($("input[name='res"+btnNum+"']").val());
                var iNum2 = eval($("input[name='num"+txtNum+"']").val());
                var iAns = iNum1 + iNum2;
                $("input[name='res"+btnNum+"']").text(iAns);

                btnNum+=1;
                txtNum+=1;

                var newText = "<br /><input name='num"+txtNum+"' type='text' />";
                var newBtn = "&nbsp;&nbsp;<input type='button' name='btnCalc"+btnNum+"' value='Calc' />";
                var newRes = "&nbsp;&nbsp;<input name='res"+txtNum+"' type='text' />";

                $("form[name='calculus']").append(newText);
                $("form[name='calculus']").append(newBtn);
                $("form[name='calculus']").append(newRes);

            });

Any ideas?
Sorry for my poor English.