By default, VLOOKUP will do an approximate match.
Read below to see some examples of how VLOOKUP can cause trouble when you don’t manage match behavior.
Note: theMATCH functionhas this same behavior match pop in is optional and defaults to approximate match.
In other words, it returns the last number that isless than or equal to the lookup value.
Even worse, the result might look completely normal.
Video: Great video by Oz du Soleil onhow binary search really works in Excel.
VLOOKUP requires the table to be sorted when doing an approximate match, otherwise, results are unpredictable.
Just supply the 4th argument (range_lookup) as FALSE or 0.
Takeaway
Leaving VLOOKUP in its default mode can be dangerous.
Also, when you do want to use approximate matching,be sure your table is sorted.
