<body>
<form id="form1" runat="server">
<div>
<asp:label id="lblNumber1" runat="server" text="Enter first value:" xmlns:asp="#unknown"></asp:label>
<asp:textbox id="txtNumber1" runat="server" xmlns:asp="#unknown"></asp:textbox>
<br />
<asp:label id="lblNumber2" runat="server" text="Enter second value:" xmlns:asp="#unknown"></asp:label>
<asp:textbox id="txtNumber2" runat="server" xmlns:asp="#unknown"></asp:textbox>
<br />
<asp:button id="btnMultiplication" runat="server" text="Multiplication" onclick="OnBtnMultiplicationClick" xmlns:asp="#unknown"></asp:button>
<br /><asp:label id="lblMultiplication" runat="server" xmlns:asp="#unknown"></asp:label>
</div>
</form>
</body>
Now on code behind (test.aspx.cs):
----------------------------------
protected void OnBtnMultiplicationClick(object sender, EventArgs e)
{
int num1=Convert.ToInt32(txtNumber1.Text);
int num2 = Convert.ToInt32(txtNumber2.Text);
lblMultiplication.Text = (num1 * num2).ToString();
}
**Validation is not done so check for Null or empty value.