Try the below formula ..

'to check for sequence AA01 to AA05
=IF(SUMPRODUCT(--ISNA(MATCH("AA"&TEXT(ROW(A1:A5),"00"),A:A,0))),"Nu mbers
missing","No numbers missing")


'to check for sequence AA01 to AA10
=IF(SUMPRODUCT(--ISNA(MATCH("AA"&TEXT(ROW(A1:A10),"00"),A:A,0))),"N umbers
missing","No numbers missing")


--
Jacob


"Stephanie" wrote:

hi, please help me here.
i just would like to know, is there a formula to detect a missing
alphanumeric number in a sequence?
Ex. if i have AA01, AA02, AA03.......AA100. how to detect of example AA03 is
missing?
please help...thanks!