Use the Number tab of the Format dialog box to specify how numerical and date values appear within a selected cell or data region. Options change depending on which value type is being formatted.
If you find that formatting options you want to use are grayed out, it means that the field's data type, which is located in the data source, and the formatting options are not compatible. For example, if the field contains numeric values but the field's data type is "string", numerical data formatting options, such as currency or decimals, cannot be applied and the numerical formatting options are grayed out.
Select to format numerical data using the options available in Report Builder.
Select how you want the numbers to appear, for example, as money or a percentage.
Specify how many decimal places you want to display.
Enter the monetary symbol that you want to display with your numerical data. By default, the symbol based on your locale is displayed.
Select to position the monetary symbol after the numerical data. By default, this box is not selected.
Use 1000 Separator
Select to insert a separator between the thousands and the hundreds place. By default, this check box is selected.
Select the format that you want to use when displaying negative numbers.
Enter a valid .NET Framework format string to customize the appearance of your numerical data. For more information about valid .NET Framework format strings, see the Microsoft Developer Network (MSDN).