The string to be used to format numbers. The default format string is "#".
Remarks
Use the following guidelines to specify the format string:
Use 0 to display either the digit in the corresponding position or 0 if
no digit is in that position.
Use # to display either the digit in the corresponding position or
nothing if no digit is in that position.
To display static text within the format string, enclose the text in single quotation
marks ('). Numerical symbols, such as the thousand separator (,) and decimal placeholder
(.), do not require quotation marks. For example: 'Number:' #,##0.00