Atable has several fields related to computer data. you want the serial number (sr. no.) field to increase by one every time you add a new record. which data type would you use for the sr. no. field?
autonumber
memo
null
blob

The answer is Autonumber.

AutoNumber data type is commonly used for primary key fields and it automatically generates a unique number for each record. This data type stores an integer that Access increments automatically as you continue adding new records. Primary keys are great but Auto numbers are also important for insuring that records are uniquely identified.  

answer; i believe that the correct answer is (calculated field);