If you can determine what will be the maximum number of rows at any
point in time, then you can use worksheet functions rather than macro,
as in this case you would not need to call a macro. I have tried
something and I believe this can be the solution to the problem.

In Cell E10, enter formula "=IF(ROW()<$A$1+10,1,"")"

Next in Cell E11, enter formula "=IF(ROW()<$A$1+10,1,"")"

Now, copy the formula down till the row number 10000 (assuming that
there would not be any need to have autonumber more than 9991)

I hope this helps

Selva V Pasupathy
visit: http://socko.wordpress.com/