VLOOKUP question

this works great and is what i have been trying to do but instead of using "Mike" i am wanting to use a number (ex. "2612") but all i get is #NUM! error and cant figure this out. Can someone help me out here and what i need to change to make numbers work and a numbers and letters work.

OR

instead of typing in Mike or 2612 can it be pointed to a cell, so instead of "Mike" could it say a1, so i could type in whatever number i wanted and the sheet would update??

Thanks