How does one use the Atl + (number) command for special characters when there is no Number Lock function?

On my previous laptop, I frequently used the Fn + Alt + [a number] to type special characters, especially when writing in Spanish. I recently purchases an Inspiron 15z Ultrabook, and although I realized there was not a numeric keypad, I was very disappointed to find that I could not activate a number lock to use the number keys on the regular keyboard with the Alt function. 

Does anyone know a work-around... other than to "insert" a special character... which is a pain when one is so used to using the Alt codes?