This would be an amazing art project to mark the years of a child's life, marriage, etc.: Buy the number in wood (or other material) and decoupage photos from that year all over the number and hang them as art work in your home.
Dental numbering or notation systems provide the dentists with a standard method for referring to particular teeth. Buzzle presents dental charts to understand tooth numbering systems. * You can get additional details at the image link.