how to add/subtract two columns?

[Anilbhide1980]

I want to add or subtract the values of the two columns i.e. fields & to get
a result in the third one. How do i do this????
I simply want to do C=A+B, in this A,B,C are three different fields/columns

 

[Douglas J. Steele]

You don't want to store calculated values in tables. As fellow Access MVP
John Vinson likes to say "Storing calculated data generally accomplishes
only three things: it wastes disk space, it wastes time (a disk fetch is
much slower than almost any reasonable calculation), and it risks data
validity, since once it's stored in a table either the Total or one of the
fields that goes into the total may be changed, making the value WRONG."

Only have fields A and B in your table. Create a query that takes all of the
fields from your table, and add a computed field to it (in an empty column
of the query grid, type C: [A] + in Field row) and use the query
wherever you would otherwise have used the table.

(Just to complete the answer, it's not possible to define calculated fields
in tables in Access)