I am unsure what you mean by base?

Are you trying to find records in your view that have either 8 or 10 in a number field?

or

Are you saying that you have a record that has a field that has multiple numbers in it? Now you want to find records that have the number 8 and the number 10 in that set of numbers?

Ok, if your field only has one number in it and you are in a table view that you now want to filter only the 8's and 10's then you need to use an "or" not an "and".

=8 or =10

if you do an "and" then it is looking for records that have both 8 or 10 in the field. since each record only has one number in the field you will not find any record that matches.

Hope this helps.