Try this - select A2 thru the end of your list. (Don't include the first
item, impossible for it to be out of sequence...)
Choose, Format, Conditional Formatting, change Cell value is... to Formula
is...
and enter the following:
=A2<A1+1
(Exactly as above - be sure it's not =$A$2<$A$1+1)
click the format button, the patterns tab, and choose a color...
click ok to see A4 in your example flagged.

"bprice" wrote:

In Excel
How do I ID the specific cell that has fallen out of sequence in a list?
Example:

A1= 1
A2= 2
A3= 3
A4= 5 (flag this cell because the number "4" is missing)
A5= 6

Do I use a formula or is there a menu option I can use?