“Hey! I’ve found an interesting website,” I said. “Do you girls want to have a look?”
“What’s it about?” asked Gemma-Rose suspiciously, and when I told her it was a maths site she groaned and didn’t look at all interested. Sophie, on the other hand, instantly plonked herself down next to me on the sofa and was very eager to find out more.
“Murderous Maths,” I said in a creepy voice. Gemma-Rose decided to come and have a look after all. Soon she was just as absorbed in the site as Sophie and me.
I placed the computer between us and then we hopped all over the site. We ended up on a page about prime numbers. We read about the Sieve of Eratosthenes, and did some prime number tricks with a calculator.
“Prime numbers are the building blocks of numbers, just like atoms are the building blocks of elements.”
I guess I always knew that but I’d never thought about prime numbers in quite that way before.
A few weeks ago I followed a link from Facebook to an article about the discovery of the 48th Mersenne prime number. I have to admit I didn’t really understand much of what I read, and couldn’t see what all the excitement was about. But today, the girls and I worked out Mersenne prime numbers together.
The 48th Mersenne prime number (which was discovered earler this year) has so many digits that if it was written in a readable font, it would stretch a distance of 50 kilometres. It has billions of digits. We did a great deal of imagining, and we wondered how anyone could write down such a large number. Don’t you love mental images that bring concepts alive? The girls just had to repeat the 50 km image to Andy when he arrived home from work.
Next, I remembered some Numberphile videos about prime numbers and we headed off to watch those:
1 and Prime Numbers (Did you know 1 is no longer considered a prime number?)
The videos were just a little complicated for Sophie (12) and Gemma-Rose (9), but with my help and some rough scribbles on a piece of paper, they understood most of the concepts. The girls certainly enjoyed the enthusiastic presentation.
We learnt that there is a connection between prime numbers and perfect numbers. I’m not exactly sure what a perfect number is, but there’s a Numberphile video on this topic. No doubt we will soon be perfect number experts!
This afternoon, Charlotte (15) came to chat with me. I couldn’t help myself. I just had to share all we’d found out about prime numbers. Fortunately she was happy to listen! So now there are 4 of us who can boast we know what a Mersenne prime number is. By the way, Mersenne was the name of a French monk who was the first person to discover these numbers. He must have had lots of quiet time to do lots of thinking.
This evening I was catching up with my record keeping. I wrote in my book:
Murderous Maths website activities
Mersenne prime numbers
Sieve of Eratosthenes
Numberphile videos: 31 and Mersenne Primes, Infinite Primes,
1 and Prime Numbers
1 and Prime Numbers
Doesn’t that sound like a good day’s maths work? None of it was planned. None of it came out of a textbook or workbook. None of it was imposed. All of it was enjoyed immensely.
“Sophie, I’ve ordered 10 of those Murderous Maths books, in a boxed set.”
“Wow! I can’t wait for them to arrive,” Sophie said, her eyes alight with delight. “I love maths!”
I love maths too. I always have. But this time round I’m learning maths in a different way to when I studied it at school. This time, I am really excited by it. (Can you tell?) The girls are excited too… even Gemma-Rose.
Our new books should arrive before the end of the week. Murdering Maths? No, our interest in maths is very much alive.