Probably best to have a 2 column table containg the letter in the left column
and the number in the right and your formula could then be:-

=VLOOKUP(A1,J$1:K$26,2,FALSE)

Drag this down as required

"FreddieP" wrote:

Hi I would like to identify rows with numbers depending on what text is in
the first column.

Lets say the first 6 rows contains the following

A
A
A
B
B
C
C
C
C
D

Then I would like in the next column to return 1 for A, 2 for B, 3 for C and
so on.