Create a recordset like:
SELECT GREATEST(field1, field2, field3, field4, field5, field6, field7) AS GreatestVal,
LEAST(field1, field2, field3, field4, field5, field6, field7) AS SmallestVal, GreatestVal-SmallestVal AS ValDifference, ValDifference + (ValDifference%2) AS ValEvenRounded
FROM <table>
Then you can refer to the values you need as columns in that table.