Being new to the Excel community, my solutions to problems are apt to be
unorthodox. With that said, I think the following worksheet formula will
return what you asked for...

=LEFT(ADDRESS(1,COLUMN(OFFSET(INDIRECT(A1&"1"), 0,B1)),4),LEN(A1))

Put the "letter(s)" in A1 and the number you want to add to it in B1and
the above formula will return the addition you seek. For example, if A1
contains AZ and B1 contains 4, the formula will return BD. Now, out of
curiosity, why are you doing this? If it is to move from one location to
another, there are more direct ways.

Rick

Another option:

=SUBSTITUTE(ADDRESS(1,COLUMN(INDIRECT(A1&"1"))+B1, 4),1,"")

Okay, I missed the direct addition... I see I didn't need the OFFSET
function call. I'll have to remember that... thanks for posting it.

I was going to remark on how much shorter your formula was than mine, but
once I removed the OFFSET function, I beat you by a couple of characters.<g

=LEFT(ADDRESS(1,B1+COLUMN(INDIRECT(A1&"1")),4),LEN (A1))

Rick