My number is 7 digits starting with a 1. For a while, I needed to add a 0 in front of the number, but that hasn't been necessary for several years, either on the AS website or any other website.

My kids, who got their account numbers in the early 90's, both have 8 digit numbers. But my son-in-law, who has had an account for less than 10 years, has a 7 digit number. AS apparently started recycling numbers at some point.