Extend found set is a viable option--especially via a script that can loop through your list of values and extend the found set for each.
You can also use this method--either manually or in a script:
Enter find mode
Enter 602 in field 1
Create a new request (See new request in requests menu)
Enter 605 in field 1
Create a new request
Repeat for each value in your list....
Either approach can be scripted if you set up a global field where the user enters the values for the search as a list. The script then loops through the list either extending the found set or creating a new request for each listed value to produce the desired found set.
And note that you can also use a range of values as your search criteria. If you entered 602...621 into field 1 as your search criteria, FileMaker will find all values from 602 to 621.