The answer to last week’s question is below, but first some facts about Friday the thirteenth:

Fear of Friday the 13th is called paraskavedekatriaphobia

Fear of the number thirteen is called triskaidekaphobia

In France, the triskaidekaphobic can hire a “quatorzieme”, or professional 14th guest.

Mark Twain once was the 13th guest at a dinner party. A friend warned him not to go. “It was bad luck,” Twain later told the friend. “They only had food for 12.”

Apollo 13 launched at 13:13 CST on April 11, 1970. The sum of the date’s digits (4,11,70) is 13. The explosion that crippled the spacecraft occurred on April 13.

And now, the answer to the question “What do telephones and grocery checkouts have in common?”