### How does Santa visit all those homes?

In *The Mathematics of Christmas* Keith Devlin notes that, “…by traveling east to west, Santa can take advantage of the different time zones, and that gives him 24 hours. Santa can complete the job if he averages 1250 household visits per second. In other words, for each Christian household with at least one good child, Santa has 1/1250th of a second to park his sleigh, dismount, slide down the chimney, fill the stockings, distribute the remaining presents under the tree, consume the cookies and milk that have been left out for him, climb back up the chimney, get back onto the sleigh, and move on to the next house. To keep the math simple, let’s assume that these 108 million stops are evenly distributed around the earth. That means Santa is faced with a mean distance between households of around 0.75 miles, and the total distance Santa must travel is just over 75 million miles. Hence Santa’s sleigh must be moving at 650 miles per second — 3,000 times the speed of sound. A typical reindeer can run at most 15 miles per hour. That’s quite a feat Santa performs each year.”

Happy festive season to everyone!