Last Monday we learned to count the number of ways to rearrange the letters in the word STOP. Six of the ways make words — STOP, TOPS, POTS, POST, SPOT and OPTS, but if you count all the ways there are to put the four letters in a row, you will find that there are 24 different orders, which mathematicians call permutations. Permutations are not usually taught in math class until college, but anyone who can add and multiply can learn the basics. Besides, rearranging words is fun!

Here’s the slide show from the event, and the video replay.

**Go deeper.** Here is a catchy song that helps you learn the formula for counting permutations and combinations. The examples are good, the rhymes are clever, but unfortunately it doesn’t explain why the formulas work.

Here’s a good explanation of why the formulas for permutations and combinations work.

https://medium.com/i-math/combinations-permutations-fa7ac680f0ac

**Discover the anagrams in your name.** Did you know that the letters of CORONAVIRUS rearrange to spell CARNIVOROUS? Or that CLINT EASTWOOD rearranges into OLD WEST ACTION? Discover the anagrams hidden in your name by Googling the Internet Anagram Server.