Guess-ta-mation Station

The school our kids attend hosts an elementary family math night once a year. Families with elementary kids come in, do crafts, win prizes, and learn some fun math based games. It's really a lot of fun.

One of the contests they have is called "Guess-ta-mation Station". They have jars and containers of various shapes and sizes filled with candy, treats, and small toys. You make a guess to the number of things in the jar and at the end of the night, if your guess is the closest, you win the jar and it's contents.

M, our little math whiz, studiously measured, counted, and sized each container trying to make his guess as accurate as possible.  He probably spend 20-30 minutes total on his guesses.

G, our 3 year old, got bored with it, and decided to guess "44" for all 10 guesses when prompted by her mom. You may remember from the "Introductions" post that double numbers like "44" or "77" are her current favorites because she thinks they're funny sounding.

Anyway, at the end of the night, they announced the winners and she won 2 of the 10! M, wasn't so lucky, or happy with his 0 for 10 result.  Do add a little extra salt to the wound, G also one the door prize.

Alge-chalk

"Alge-chalk", what the kids decided to call their sidewalk chalk algebra fun this weekend.   I wanted to call it "chalk-ebra", but I was over ruled.


Apparently this was so much fun that they want to do it again.

Why Pi

Why do we call it "pi" and not some other Greek letter?  Well, according to this article, "How a farm boy from Wales gave the world pi", we owe it to William Jones who published the popular book "Synopsis palmariorum matheseos" which was sort of a primer on the current state of mathematics in the early 1700s.


This book contains the first recorded use of the symbol pi to represent ratio of a circle's circumference to its diameter (page 263).   It's believed he chose this as it was the first letter in the Greek word for perimeter or periphery.

When I asked the kids to guess when it was first used, they had a bunch of wild guesses ranging from 1000 BC to 400 AD, but nothing near as recently as the early 1700s.   I must admit, I was surprised to learn it was so late as well.  I guess you never know.

73 Is So Emirp

I read an article today about the Golden State Warriors getting their 73rd win, and the properties that make the number 73 interesting (Golden State and the Mathematical Magic of Seventy-Three).  Apparently there are quire a few of them!  It is the 21st prime number, the number of books in the Catholic Bible... and the list goes on.

One of the things mentioned about 73 that jumped out at me was that it is the "sixth emirp".  What's that you say?  You've never heard of an emirp?   Well neither had I.

Emirp is "prime" spelled backwards.  As you might guess, it is a prime number that, if you reverse the digits, you get another number that is also prime.  This is restricted to non-palindromic base 10 numbers.   The first few are 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, etc. (OEIS A006567).    Note that the primes 2, 3, 5, 7, 11, 101, 131, etc.  are excluded because they are palindromic.

When sharing this with the kids over dinner, G, our precocious 3 year old,  had to go potty.  I offered to help.  She said, "No, I can do it myself.  You should stay and finish talking about numbers."

Vi Hart

I'm not sure how I originally stumbled on Vi Hart's videos, but the way they indirectly approached some pretty advanced math concepts through haphazard stream of conscious doodling was fun and appealing, and I knew immediately that my kids would love them.

You can see most of her videos on her YouTube channel, or catch up with all of her latest musings on her personal blog.  Be sure to checkout the "hexaflexagon" videos -- they are some of my kids favorites.  

She's also got a YouTube playlist of a bunch of her pi-related videos, although I don't think these are her best work.