=SUMPRODUCT((A1:A10<"")/COUNTIF(A1:A10,A1:A10&""))

--
HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)

"EXCEL$B!!(BNEWS" wrote in message
...
hi,

there are a column made up from , say, a, b, c, a, c, d ,a,c,e

how to know the number of types,

thanks