[AccessD] Column Formulae

In SQL, I can create a calculated column; i.e. ExtendedAmount = 1 + TaxRate
* (Quantity * Price).
Can I store said result in an actual column in Access (MDB)? Aside from the
fact that it's not a good idea to store calculations in columns, I am
retrofitting an existing db so I have limited choices here.
I have toyed with the default value attribute but so far have not had
success when attempting to reference other columns in the table.
So let me pose the question as simply as I can.
Given these columns:
Quantity    int
Price       currency
Extended    currency
Is there a way to make the value of Extended = Quantity * Price? I do not
want to do this in the front end. I want to do this in the table definition.
TIA,
Arthur