On Sat, 17 Apr 2010 21:04:04 +0100, "Rob"
wrote:

Thanks Ron, another brilliant way to achieve the result.

Ta, Rob

Here's another way:

=IF(AND(LEN(SUBSTITUTE(A1," ",""))=9,MOD(SUMPRODUCT(
--MID(SUBSTITUTE(A1," ",""),{1,2,3,4,5,6,7,8,9},1),
{8,7,6,5,4,3,2,10,1}),97)=0),"Valid","Invalid")

--ron