When you run a query, it could return text when you really wanted a date or some other number format.
All you need to do is surround the query expression with the Format function. Here, we are stringing together the contents of field aaa and bbb, perhaps to create an account number.
Combine area code and phone number fields into one by: =FORMAT([aaa]&[bbb],"000-000-0000)
Add two values and ensure you get 2 decimals: =FORMAT([aaa]+[bbb],"0.00")
Source: Microsoft Articles