Excel - Create serial numbers

Issue

I have an Excel file that shows different values of schedule of correspondence and some of the mails are gone to different addresses and the mail ref. colum (showed only once). I want to count the mails serially. How to create exact serial numbers?

I want to skip the rows that have no values i.e. ref of the mails.

Example :

04/02/2010      C. Fox  Al-Futtaim Carillion    M. LEWIS 

04/02/2010      A. Simp Al-Futtaim Carillion    I. AL-QUDAH 
M. LEWIS 
04/02/2010      R. Pal  Al-Futtaim Carillion    A. Kumar 
M. LEWIS 

Please provide a formula.

Solution

You Can Use ROW() function for generating serial numbers,
for example,

In A1 cell write:

=ROW() and press Enter,that will give 1 as answer.

Now click on A1(i.e. Select it)-> Press Ctrl+Shift+Down(to select the below fields which will get its serial now..) -> After selecting the column Goto--EDIT->FILL->DOWN

This will fill all the cells with the respective ROW number...

Thanks to Jyot Patel for this tip.