hi jt,

the first part (=COUNTA(A1:A100)) is all entries
the second part of the formula is the unique entries

=COUNT(1/FREQUENCY(A2:A100,ROW(INDIRECT("1:"&ROWS(A2:A100)) )))

subtract the second part from the first gives the number of duplicates

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isabelle



Le 2012-04-09 21:20, john taiariol a écrit :
On Apr 9, 6:59 pm, wrote:
hi jt,

=COUNTA(A1:A100)-COUNT(1/FREQUENCY(A2:A100,ROW(INDIRECT("1:"&ROWS(A2:A100)) *)))

--
isabelle

Le 2012-04-09 17:27, jt a écrit :



Hi there,
I have a column on numbers and I was wondering if I can add a formula
to the bottom of the column that would tell me how many dublicate
numbers there are.

thanks in advance for your time.

sorry but it doesn't seem to work, maybe i need to reword it, i would
like to count the number of unique entries....