Automatically add comma to large numbers and dispay in currency format in ASP.Net C#

Here I have created sample that will help you out.

and create specific culture as per your country i.e.

CultureInfo.CreateSpecificCulture("hi-IN")

HTML

<div>
    <table border="0" cellpadding="0" cellspacing="0">
        <tr>
            <td>
                Enter First Number :
            </td>
            <td>
                <asp:TextBox ID="txtNumber1" runat="server" />
            </td>
        </tr>
        <tr>
            <td>
                Enter Second Number :
            </td>
            <td>
                <asp:TextBox ID="txtNumber2" runat="server" />
            </td>
        </tr>
        <tr>
            <td colspan="2">
                <asp:Button Text="Multiply" runat="server" OnClick="Multiply" />
            </td>
        </tr>
        <tr>
            <td colspan="2">
                <asp:Label ID="lblResult" runat="server" />
            </td>
        </tr>
    </table>
</div>

C#

protected void Multiply(object sender, EventArgs e)
{
    if (!string.IsNullOrEmpty(txtNumber1.Text) && !string.IsNullOrEmpty(txtNumber2.Text))
    {
        decimal num1 = decimal.Parse(txtNumber1.Text);
        decimal num2 = decimal.Parse(txtNumber2.Text);
        lblResult.Text = (num1 * num2).ToString("N2", CultureInfo.CreateSpecificCulture("hi-IN"));
    }
}

VB

Protected Sub Multiply(sender As Object, e As EventArgs)
	If Not String.IsNullOrEmpty(txtNumber1.Text) AndAlso Not String.IsNullOrEmpty(txtNumber2.Text) Then
		Dim num1 As Decimal = Decimal.Parse(txtNumber1.Text)
		Dim num2 As Decimal = Decimal.Parse(txtNumber2.Text)
		lblResult.Text = (num1 * num2).ToString("N2", CultureInfo.CreateSpecificCulture("hi-IN"))
	End If
End Sub

Screenshot

Hi,

I have created sample.based on TextChanged Event of TextBox.

HTML

<div>
    <table border="0" cellpadding="0" cellspacing="0">
        <tr>
            <td>
                Enter First Number :
            </td>
            <td>
                <asp:TextBox ID="txtNumber1" runat="server" OnTextChanged="Calculate" AutoPostBack="true" />
            </td>
        </tr>
        <tr>
            <td>
                Enter Second Number :
            </td>
            <td>
                <asp:TextBox ID="txtNumber2" runat="server" OnTextChanged="Calculate" AutoPostBack="true" />
            </td>
        </tr>
        <tr>
            <td colspan="2">
                <asp:Label ID="lblResult" runat="server" />
            </td>
        </tr>
    </table>
</div>

Code

protected void Calculate(object sender, EventArgs e)
{
    decimal num1 = !string.IsNullOrEmpty(txtNumber1.Text) ? decimal.Parse(txtNumber1.Text) : 0;
    decimal num2 = !string.IsNullOrEmpty(txtNumber2.Text) ? decimal.Parse(txtNumber2.Text) : 0;
    lblResult.Text = (num1 * num2).ToString("N2", CultureInfo.CreateSpecificCulture("hi-IN"));
}

Screenshot