Formula

[Rosie]

Is it posible to put in a formula to ensure there are no duplications when
putting in numbers in cell?

 

[Peo Sjoblom]

One way

http://www.cpearson.com/excel/NoDupEntry.htm

Regards,

Peo Sjoblom

 

[Jason Morin]

There's a simple method using COUNTIF and Validation. See
Debra Dalgleish's website for specific instructions:

http://www.contextures.com/xlDataVal07.html#Unique

HTH
Jason
Atlanta, GA