excel Naming constants

Virtually every experienced Excel user knows how to create cell and range names (although not
all Excel users actually do so). But most Excel users don’t know that you can use names to refer
to values that don’t appear in your worksheet — that is, constants.
Suppose that many formulas in your worksheet need to use a particular interest rate value. One
approach is to type the interest rate into a cell and give that cell a name, such as InterestRate.
After doing so, you can use that name in your formulas, like this:
=InterestRate*A3
An alternative is to call up the New Name dialog box (Formulas➜Defined Names➜Define Name)
and enter the interest rate directly into the Refers To box (see Figure 3-4). Then you can use the
name in your formulas just as if the value were stored in a cell. If the interest rate changes, just
change the definition for InterestRate, and Excel updates all the cells that contain this name.