easy, please help me

[M.J. Nielsen MN3 USN]

All I need to do is make a spreadsheet that limits me
form using the same number twice.

 

[Arvi Laanemets]

Hi

P.e. you want, that in range A1:X100 any entry must be unique. Then:

Select A1

From menu, select Data.Validation.Custom
Formula=COUNTIF($A$1:$X$100;A1)<2

Copy the cell A1 and paste to range A1:X100


Arvi Laanemets

 

[John McCormack]

You might be able to use conditional formatting to at least highlight if the
number has already been used e.g.

select cell A2 and then choose
Format ->Conditional Formatting and select formula is and enter the
following formula
=COUNTIF(A:A,A2)>1
an format pattern as red

Copy this format down to the area you require , and any duplicates will be
highlighted as red.

Regards

John McC
Tipperary

 

[David McRitchie]

You can do that with validation
http://www.mvps.org/dmcritchie/excel/validation.htm

Unique value in a column « David Hagar (Disallow Duplicate)
=COUNTIF($A$1:A1,A1)=1 for Column A

When using validation or filtering the object is to produce
a True or a False condition.

If my page doesn't help you then try Debra's page at contextures.com
in the related links at bottom of the above page. For more information
on COUNTIF, you might look at both HELP and at John Walkenbach's
COUNT, Tip 52:Cell Counting Techniques
http://www.j-walk.com/ss/excel/tips/tip52.htm