Converts a value to a number, using following rules:
|If value is or refers to||N returns|
|A number||That number|
|A date, in one of the built-in date formats available in Microsoft Excel||The serial number of that date|
|An error value, such as #DIV/0!||The error value|
Source: Microsoft Office website
Where (value) is a value to convert to a number
Excel by default converts values to numbers, like Jan 01, 1900 is serial number 1 and Jan 09, 2017 is serial number 42736 because there are 42736 days after Jan 01, 1900. The N function is used for comparability with other spreadsheets programs.