Storing calculated values

[BB]

I have a form with 2 subforms. Both subforms include charges (quantity * unit amount).
I want to get a grand total of the 2 subforms and store it in the main form’s underlying table.
I was going to use SetValue, but can’t seem to get it worded right. I know I shouldn’t be storing a calculated value, but I feel I need to. Can someone tell me how to do this, please? Or is there some other way to do this?
Thanks

 

[Carol]

NEVER store calculated fields within your database. Use a query to include the calculation and then use the results of this query as your recordsource.

 

[BB]

No, I really need to store this calculated value.

 

[R. Hicks]

Carol ... never say "Never: ....

There are special rare cases where this may be necessary. I agree that it should be a "last resort" measure.

RDH