Question: I'm trying to add comma separators to a number. I've tried the advice here: [add commas using String.Format for number and](https://stackoverflow.com/questions/2545633/add-commas-using-string-format-for-number-and) and here: [.NET String.Format() to add commas in thousands place for a number](https://stackoverflow.com/questions/105770/net-string-format-to-add-commas-in-thousands-place-for-a-number) but I can't get it to work - they just return the number without commas. The code I'm using is here:

`public static string addCommas(string cash) {
 return string.Format("{0:n0}", cash).ToString();  

 }`

Where am I going wrong?

Thanks.

---

Update: Hi all, thanks for your help, but all of those methods are returning the same error: "error CS1502: The best overloaded method match for 'BishopFlemingFunctions.addCommas(int)' has some invalid arguments" (or variations therof depending on what number type I'm using.) Any ideas?

Answer: 
In order to apply number formatting you have to pass `cash` as a number type (int, double, float etc)
i have a method on my custom class to convert any numbers

```
public static string ConvertToThosandSepratedNumber(object number)
{
    string retValue = "";
    retValue = string.Format("{0:N0}", Convert.ToDecimal(number));
    return retValue;
}

```