The formula suggested by pdberger does exactly what you ask. Just use a
separate area in your worksheet to populate with two columns exactly as
pdberger said. For example, put them in K1:L5. Then, if you enter a
value in A1, B1 will show the corresponding value with:

=VLOOKUP(A1,$K$1:$L$5,2)

HTH
Kostis Vezerides