Need help with a formula

[Ron]

Here is my problem. I have to enter apt # on a spreadsheet for tracking
material used. The problem is I am always finding duplicates. What I would
like to be able to do is this.
Enter the unit number ain a single cell. That will then move to a specific
row in numeric order. If i enter a number that already been entered it will
flag me.

Does this make sense.

 

[Vital_ar]

Dear Ron,
Is it should be highlited if you enter a Apt #, which is alredy entered?
Then Conditional Format ("Format only unique or Duplicate values" in Excel
2007) may help you.

Thanks & Regards