You want to use an Aggregate Query to return just the maximum values of the FilteringField (and nothing else).
Then you can either create a new query based on your original table and this aggregate query, joining on the FilteringField field and returning the NumberstoFilter field,
or you can use this aggregate query in a nested query to do the same thing in a single query.
Here is what the SQL code structure of the nested query would look like:
Code:
SELECT NumberstoFilter
FROM MyTable
WHERE FilteringField in
(SELECT Max(MyTable.FilteringField)
FROM MyTable);