Where do I create the table? On a seperate sheet?
You can create the table anywhere you want. In my example I put it on the
same sheet as the cell that you're checking. A lot of folks like to put
lookup tables on a separate dedicated sheet just for tables.
Let's say you put the table on Sheet2 in the range A1:B7.
Sheet1 A1 is the number you want to lookup and you want the result in Sheet1
B1. So, you'd enter this formula on Sheet1 in cell B1:
=IF(A1="","",VLOOKUP(A1,Sheet2!A1:B7,2))
Or, you can give the table a defined name and use that name in the formula.
Assume the table is on Sheet2 in the range A1:B7.
Navigate to Sheet2
Select the range A1:B7
In the name box, that little box directly above column A, type in a name for
the table. Example: MyTable
Then hit ENTER
Now you can use that name in the formula:
=IF(A1="","",VLOOKUP(A1,MyTable,2))