The LOOKUP function will automatically ignore errors, so the only thing left to match are the 1s. It will scan through the 1s looking for a 2 that will never be found. We are using 2 as a lookup value to force LOOKUP to scan to the end of the data. How will LOOKUP ever find the number 2 in an array that contains only 1s and errors? It won't. Now, you may have noticed that the lookup value is the number 2. This may seem puzzling. Don't worry, there is a method to this madness :)
