How to display numeric in 3 digit grouping

Question

How to display a numeric numbers in 3 digit groupings.

For Ex: 1234 to be 1,234 or 1 234

Answer 1

From the The Numeric ("N") Format Specifier section in Standard Numeric Format Strings:

double dblValue = -12445.6789;
Console.WriteLine(dblValue.ToString("N", CultureInfo.InvariantCulture));
// Displays -12,445.68

Console.WriteLine(dblValue.ToString("N1", 
                  CultureInfo.CreateSpecificCulture("sv-SE")));
// Displays -12 445,7

int intValue = 123456789;
Console.WriteLine(intValue.ToString("N1", CultureInfo.InvariantCulture));
// Displays 123,456,789.0 

Answer 2

Try this:

String.Format("{0:n0}", yourNumber);

If you want spaces instead of commas try this:

String.Format("{0:n0}", yourNumber).Replace(",", " ");

Edit: Marc makes a good point about being cuturally aware so this would be a better way to replace the group separators:

String.Format("{0:n0}", yourNumber)
    .Replace(NumberFormatInfo.CurrentInfo.NumberGroupSeparator, " ");