## Plus Advent Calendar Door #11: Ding-dong

Submitted by Marianne on December 11, 2010Bells can do a lot more than just jingle! In fact, being a decent bell ringer requires razor-sharp mathematical precision and a vast memory. And just 16 bells are enough to provide your neighbours with over a million years of non-repeating bellish amusement. Find out how with Ringing the changes.