What Formula?

[Chris]

I have a worksheet that identifies invalid responses to a
survey by participant ID and question number. Structure of
worksheet is:

40 question numbers in the 1st row across the top of the
worksheet--one in each cell C1:AP1. 100 survey
participant IDs in Column A--A2:A102.

If a participant chose an invalid response to one of the
questions, an X was placed in the respective cell that
coorelates to the participant ID and question number. The
participant might have chosen more than one invalid
response meaning there might be 2 or more X's on the same
row.

I want to put a formula in the column B cell that will
return the question number(s) of any cells that have an X
in them for each participant.

I tried =IF(ISBLANK(H42)," ",H1)which works great for one
question at a time. My problem is I have 40 questions and
I need the formula to check each cell in the row for an X.

Hope I didn't muddle this too much.
TIA
Chris