MICROSOFT EXCEL 2003

Can anyone help. IF THE LETTER “A” IS ENTERED INTO A CELL BETWEEN (A1:A40) THEN THE NUMBER Fig”1″ IS PLACE IN CELLS (B1:B40) If another “A” IS ENTERED BETWEEN (A1:A40)THEN Fig “2” IS PLACE IN CELLS (B1:B40)AND SO ON NUMBERING CELLS IN SEQUENTIAL ORDER 3,4,5. SO IF THERE ARE 5 “A”,S IN ROW (A1:A40) ROW (B1:B40) WOULD HAVE THE NUMBERS 1,2,3,4,5. BUT NOW I WHANT A CHOICE OF LETTER’S I WANT BE ABLE TO USE A,B,C AND D IN ROW (A1:A40) EACH LETTER GIVING IT’S OWN SEPERATE COUNT AS WE GO DOWN THE ROW (A1:A40) SO IF I ENTER “A” THAT WILL HAVE THE NUMBER 1 IF I NOW ENTER “B” THATS THE FIRST “B” ENTERED SO IT WILL BE NUMBERD 1 ALSO IF I ENTER ANOTHER “B” THATS 2

ITEM A 1
ITEM B 1
ITEM B 2
ITEM A 2
ITEM C 1
ITEM D 1
ITEM A 3