"storing" a calculated value in plsql function ?

I have created a function (PLSQL) that does a complex select with joins on various
tables and views, and returns a table.

In the resultant table, I have raw data, and adjusted data. The adjusted data i
all adjusted by a common factor, which is calculated in the select. Presently, I
calculate this same adjustment factor several times in the select.

Is there a way to reference this value, multiple times, once it is calculated? Or
would I have to create a 2nd select that calculates this adjustment factor, and
stores it in a PLSQL variable< and if I do that, can I reference this stored value
in the select?

-- 
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neither liberty nor safety."
                        -- Benjamin Franklin