Ordering Patterns
 

I'm working on a spreadsheet that shows an ordering cycle of a customer. The
data shows in which months a customer orders a product.

The format of the data is in column A show customer number, B through ??
Shows Month 1 to ??

I need a formula that shows in which month a customer stops ordering. The
information is updated on a monthly basis so if a customer has left will
change if they order within the next period. There is over 100 months of
data to look at. But essentially if a forumula that will analysis 30 or so
months is avail it would cover my needs

If anyone has any ideas of what sort of formula to use would be appreciated.

All help is greatly apprecaited.

Regards
Tom Hewitt