I know it's a little off-topic, but following up with the solution presented by Jonas Bøhmer, actually I think that MOD is the best solution to your example.
If your intention was to limit the result to one digit, MOD is the best approach to achieve it.
ie. Let's suppose that VLOOKUP(A1, B:B, 1, 0) returns 23. Your IF formula would simply make this calculation: 23 - 10 and return 13 as the result.
On the other hand, MOD(VLOOKUP(A1, B:B, 1, 0), 10) would divide 23 by 10 and show the remainder: 3.
Back to the main topic, when I need to use a formula that repeats some part, I usually put it on another cell and then hide it as some people already suggested.