Filtering on calculated difference between two dates

We have created a generic inquiry which calculates the difference between the last user password change date and today() to get a number. This works.

We now want to use that number to filter the records.

e.g daysSincePWChange is greater than 0.

The filter works if we use EQUAL or STARTS WITH and a given number, which means the result is being treated as a string. 

What can we do to ensure the calculated results are treated as numbers?

Regards