Validation for D4:

=LEN(D4)=7

Highlight D5:D100 and then use the Validation:

=AND(LEN(D5)=7,COUNTIF($A:$I,D5)=1)

--
HTH

Sandy
In Perth, the ancient capital of Scotland
and the crowning place of kings


Replace @mailinator.com with @tiscali.co.uk


"SiH23" wrote in message
...
Hi,

I would be most grateful if someone could offer some help or advice.

I wish to Validate a range of cells from D4 to D100 which will only allow
the following:

1. only a 7 figure number to be entered.
2. to not allow a duplicate 7 figure value to be entered.

Many thanks,

Simon.