See, I am doing a new thing! Now it springs up; do you not perceive it? I am making a way in the wilderness and streams in the wasteland. (Isaiah 43:19)
#FridayThe13th occurs 688 times in a full-cycle of the Gregorian calendar. This makes Friday the most common day for a 13th to fall on -- but not by much. Thursday and Saturday are the rarest 13ths. They each occur just 684 times every cycle.
Fun fact: If you shout "Show yourself, coward" when you get home your dog will wake up and run into the room because it does not have a good grasp of English but is happy to see you.
An "emirp" is a number that's prime backwards and forwards. The first thirty are: 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, 149, 157, 167, 179, 199, 311, 337, 347, 359, 389, 701, 709, 733, 739, 743, 751, 761, 769, 907, and 937.