Should I store a calculate value in my database along with the variables?

Question

In all the applications I have made where a database is used I typically store the calculated value along with the variables needed to calculate that value. For example, if

Answer 1

The standard approach is not to store this kind of calculated values - it breaks normalization.

There are cases you want to store calculated values, if it takes too long to recalculate, or you are running a data warehouse etc. In your case, you want stick to the normalization rules.