autonumber

hi
In a table, i've pasted 800 records in a file under field serial number and
have one cell with property "autonumber". The autonumber rises to value 800.

Again, when i delete all 800 records, and adds fresh ones, the "autonumber"
value starts from 801 onwards.

This makes the file size goes to as big as 45 MB.

Please suggest to optimize file and restart autonumber method.

thanks
deepak