Speed limits in Northern Ireland are in miles per hour, but the Republic uses kilometres per hour. We have a Dublin car while we’re here and one of the most useful tips the Internet taught me was that miles:km roughly follows the Fibonacci sequence.
Speaking of the Fibonacci sequence, I just remembered that I used to play the Rockabye Baby version of Lateralus to the older kid when he was a baby. He didn’t seem to particularly like those albums but it amused me. https://youtu.be/V2dJZG18CKM