Without knowing all the particulars, I can only provide a suggestion.  If you
are looking to find records in a table that need calculations based on
certain criteria, I would suggest a query.  If you are going to be making
changes to the values in the fields, then it would most likely need to be an
Update query.
To do this, what you need to do is determine the criteria on which records
should be selected.  You then need to write criteria into the query so that
it will affect only the records you want.  In the query builder, there is a
row called Update To:
This row populates a row in the table with the value entered.  That value
can be a hard coded value, a field from a related table, or can accept either
Access functions or user defined functions.
So, if you need to do a calculation on a field, you would write a VBA
function that performs the calculation and returns the results you want
stored in the field.  You would pass it a value or values it would need to
perform the calculation.