One way,

Say your previously used numbers are in column B and your proposed new
number is in A1. Try this formula

=IF(COUNTIF(B1:B100,A1),"Already used","")

Mike

"AMH" wrote:

Hi, looking for soem help, I have a spreadsheet that generates randon
numbers, I want to check against a lsit of numebrs to see if the random
number generated have already been used. I can identify the number in a list,
however I am looking for a formula to highlight that the number has already
been used.

I was thinking of putting a 1 in the column beside the number in the list as
it appears so that I know it has been used before. Obviously if I jsut use a
formula that will update the next time a new number is generated.

I can do this very easily with a macro however for this problem I cannot use
a macro I need to use formula. Really looking for formula that pastes a value
into a cell if such a thing exists ?