Problem:

We want to create a formula to check whether each number in column B appears in List 1 (Column A).
For each successful search, the formula should return that number.
However, if an exact match is not found, the formula should return a text message to that effect, rather than an error.

Solution:

Use the IF, ISERROR, and VLOOKUP functions as shown in the following formula:
=IF(ISERROR(VLOOKUP(B2,$A$2:$A$9,1,FALSE)),\"Number Not Found\",VLOOKUP(B2,$A$2:$A$9,1,FALSE))