how to disable numeric keypad. i can only type by holding down fn key, help

Hello,  My dell latitude CPx J650GT keyboard numeric keypad locked up. It only let me type the letters when i hold the fn key down first. I thought that it was the reverse, where you have to hold down the fn key to use the numeric keypad? I just bought this computer and does not know how to fix this, please help. It may be a simple setting which i'm not familiar with. Thanks for any help. I tried to reset the setting in bios so far without any help.

 

Mike