I want add a number to a text value and have it appear in
output. Original value column Extension is a text that I
want to add 2100, but I want to have it output to a text.

Using Northwind database, table Employees:

Code:
Select 
  (E.EmployeeID) as 'EmployeeID_ab',
  (E.Extension)  as 'Extension_ab' 
From Employees E
Returns rows like this:
Code:
EmployeeID_ab  Extension_ab
...