You are calling the Object.ToString method which has no overload with one parameter. First you must cast the object to whatever type it is, then call the ToString method.

For example, if it is a decimal, then try this:

this.dollarString = ((decimal)(ds.Tables[0].Rows[0][0])).ToString("C");


>This works fine, but if I try to change to:
>
>this.dollarString = ds.Tables[0].Rows[0][0].ToString("C");
>
>I get the error:
>
>No overload for method 'ToString' takes '1' arguments
>
>How do I format the numeric value in the DataSet to display in currency format?
>