Assuming that A1:L10 contains your data...

=SUMPRODUCT(--(ISNUMBER(MATCH(A1:K10,{"AAB","BMN"},0))),B1:L10)

OR

=SUMPRODUCT(--(ISNUMBER(MATCH(A1:K10,N1:N2,0))),B1:L10)

....where N1:N2 contains your list of letters, such as 'AAB". You can
add more letters for which to search in both formulas.

For the first formula, you can add them to the array constant
{"AAB","BMN","BBC","CCG",...}. For the second formula, you can add to
the list N1:N2. Make sure you change the reference accordingly.

Hope this helps!

In article ,
"Peter FS" <Peter wrote:

Hello everyone, I am looking for a formula that can look up several different
letter combinations and calculate the values in the corresponding cells. An
example:

There is a host of letters such as "AAB", "BMN", etc. in multiple cells at
the coordinates of 13 columns and multiple rows. Each of those cells has an
adjacent cell that contains a value.

I need the formula to sum the values of the cells that match each of those
particular letter combinations.

Appreciate your help