VAT Numbers

My girlfiend and I had a meal at an Italian restaurant. After paying for the meal I picked up the receipt and was amazed to see it quoting the VAT registration number 123 4567 89. I immediately thought that this VAT number was utter boloney. I later decided to check the validity of the VAT number on the Europa website. The number was complete rubbish and so my initial thoughts seem to have been proven correct. Does anyone know of any legitimate reason why a trader would quote this VAT number?

Also I remember (in the distant past) being told of another way of checking VAT numbers i.e. through a simple multiplication exercise. Does anyone know of this?
Dave