To specify numeric criteria for an operation, you supply a numeric value as part of the string expression that forms the criteria argument.
Suppose that you are performing the DLookup function on an Employees table to find the last name of a particular employee, and you want to use a value from the EmployeeID field in the function's criteria argument. You could construct a criteria argument like the following example, which returns the last name of the employee whose EmployeeID is 7:
=DLookup("[LastName]", "Employees", "[EmployeeID] = 7")