Hot cross buns
Image credit: By Lausanne Morgan, U.S. Air Force [Public domain], <a href="https://commons.wikimedia.org/wiki/File:Hot_cross_bun.jpg">via Wikimedia Commons</a>

Although hot cross buns are typically associated with the Easter season in general and Good Friday in particular, they’re a tasty treat whenever you happen to eat one—which (unless it’s around Easter) may mean baking them yourself. Although I don’t know why September 11 came to be National Hot Cross Bun Day, it seems like as good a time as any to remember the timeless religious and/or mathematical significance of the X/+/† symbol in convenient pastry form. (And if you’re baking them yourself, why not go crazy and add a few alternative designs: ÷, #, or √, for example.)