I am currently having a html code as:
<form>
<input type="text" name="price1" size="14" value="Rs.900" readonly="readonly"/>
<input type="text" name="price2" size="14" value="Rs.600" readonly="readonly"/>
<input type="text" name="price3" size="14" value="Rs.500" readonly="readonly"/>
</form>
<form name="qty">
<input type="text" name="quant1" id="id1" size="14" value="0"/>
<input type="text" name="quant2" id="id2" size="14" value="0" />
<input type="text" name="quant3" id="id3" size="14" value="0" />
</form>
<input type="button" onclick="calculate()" value="Submit" />

On clicking the submit button i want the value entered in qty form gets multiplied by corresponding price & gets returned using a javascript function.
Also how to validate the qty form, so as to allow only numeric values.
Please respond.

Thanks in Advance

Can you show the calculate function that you've wrote so far?

<html>
<head>
<style type="text/css">
.style1
{

width:500px;
background-color:#b0e0e6;
}
</style>
<script type ="text/javascript">
function validate(f11)
{
var a =f11.t2.value;
var b =f11.t3.value;
var c =/^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
var d =f11.t4.value;
var x = /^([A-Za-z0-9]){6,10}$/;
var y = f11.t5.value;
var passwd= /^([A-Za-z0-9_\-\.\@\)\(\+]){8,20}$/;
var phnoe = /^([0-9]){10,12}$/;
var phno = f11.tp.value;

if(document.f1.t1.value=='')
{
alert("please fill the field");
return false;
}

<!-- validation using regular expression so that phone no must be within 10 to 12 and contain numbers only-->

if(phnoe.test(phno)== false)
{
alert("please re enter valid phone no ");
return false;
}
<!-- validation using regular expression so that password must not contain some special charector only & should be within 8 to 20-->
if(passwd.test(b)== false)
{
alert("your password is not between 8 to 20 or containing unsupported charector");
return false;
}

if(a!=b)
{
alert("please re enter");
return false;
}
if(c.test(d)== false)
{
alert("please re enter valid email id ");
return false;
}
<!-- validation using regular expression so that username must not contain special charector & should be within 6 to 10-->
if(x.test(y)== false)
{
alert(" username must not contain special charector & should be within 6 to 10");
return false;
}

<!-- validation for dropdown list-->

if(document.f1.car.selectedIndex <=0)
{
alert("please select a car");

return false;
}

<!-- validation for radio button-->

var radioselected=false;
for(i=0; i<document.f1.gender.length; i++)
{
if(document.f1.gender.checked)
radioselected=true;
}
if(!radioselected)
{
alert("please select at least one gender value");

}

<!-- validation for checkbox -->
if (document.f1.c1.checked == false &&
document.f1.c2.checked == false &&
document.f1.c3.checked == false)
{
alert ('You didn\'t choose any of the checkboxes!');
return false;
}

}
</script>
</head>
<body bgcolor = "olive">
<center>
<div class ="style1" >

<form name ="f1" onsubmit = "return validate(this)">

<h1> form validation using javascript </h1>
name<input type ="text" name="t1" value=""/> <P>

phone no<input type ="text" name="tp" value=""/><P>
password:<input type ="password" name="t2" value=""/> <P>
re enter :<input type ="password" name="t3" value=""/> <P>
email ::<input type ="text" name="t4" value=""/> <P>

<!-- user name field-->
desired username: <input type ="text" name="t5" value=""/> <P>

<!--drop down list-->
car :<select name="car">
<option value="0" selected="selected">Select One</option>
<option value ="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value= "bike">bike</option>
<option value ="santro">Santro</option>

</select> <p>
<!-- radio button field -->
select geder:<input type="radio" name="gender" value="female ">FEMALE
<input type="radio" name="gender" value="male ">MALE <p>

<!-- checkbox field -->
select course :
<input type="checkbox" name="c1" value="c++" />C++
<input type="checkbox" name="c2" value="java" />CORE JAVA
<input type="checkbox" name="c3" value="os" />OS <p>

<input type ="submit" value ="click">
</form>

</div>
</center>
</body>
</html>