Best way to generate order numbers for an online store?

Question

Every order in my online store has a user-facing order number. I\'m wondering the best way to generate them. Criteria include:

• Short
• Easy to say over the

Answer 1

http://blog.logeek.fr/2009/7/2/creating-small-unique-tokens-in-ruby

>> rand(36**8).to_s(36)
=> "uur0cj2h"