Author: Emily Fleming

Latin Squares

Select the 16 Jacks, Queens, Kings and Aces from a pack of cards. Try to put them in a 4 by 4 square so that each rank (J, Q, K, A) and each suit (Clubs, Diamonds, Hearts, Spades) appears only once in each row and column.

This puzzle is an example of a Latin square. Latin squares are used in medical trials to ensure every participant is allocated to each treatment for the same time period to prove which is the best treatment. See these links for some more info – mathsisfun, wikipedia and nrich.

We are really missing having maths club in person, and we missed the maths camps in Africa in the summer … but we are so happy that circumstances have meant the launch of the Virtual Maths Camp. The puzzle above is going to appear on the 6 of spades in our card deck! Please check out the idea behind our maths club app  which can be accessed online here. We are very keen to translate our activities into French so that they can be used in countries like Togo. If you would like to help with translation, please get in touch with Emily Fleming at [email protected].

The Game of Life

From this great article in Plus magazine

Go to this https://bitstorm.org/gameoflife/ and colour in a 2 by 2 square on the screen like this:

Press start. Nothing should happen to the square. Why?

Well, because each yellow square has exactly 3 neighbours so all survive. There are no other cells that have exactly 3 neighbours so no new cells are born.

Now try with a three by three cell:

Press start. What happens?

Try to work out on paper what you think would happen for a 4 x 4 shape.

Then test your answer.

How about 5 x 5, 6 x 6 and 7 x 7?

Have a play around and see what fun patterns you can make.

You might like to read the article from Plus Maths or even try this question from the 1996 British Informatics Olympiad.

Factors and Multiples Chain

Today we worked on this lovely puzzle from Nrich.

Choose a starting number from a 1-100 square and cross it out.

Then choose a factor or multiple of that number.

Keep crossing out factors or multiples of the last number in the chain.

For example, Charlie started with 60, 30, 6, 96, 16, 32, 8, 56, 7, 21, 42,…

What’s the longest chain you can make?

There is an interactive place to play here

When you are using the activity make sure you only have a bracket at the start and the end … this attempt isn’t quite right:

There are two chains, rather than one continuous one.

But it can be fixed by swapping the 60,90,45 and 15 around:

Now it is a chain of 38 steps

Email Mrs Fleming on [email protected] if you can do better than 38 steps …

Sprouts

In honour of John H. Conway, today we present a game that he co-invented with Michael S. Paterson while they were both at Cambridge.

It is called Sprouts, and the rules are summarised by Nrich here.

Anyone can play, so find someone in your house and play a few games, then try and discover some of the maths behind it by working through this article.

Modelling Coronavirus on Geogebra

Ben Sparks gives instructions to do some disease modelling on Geogebra – so you can see the maths behind the government advice to “flatten the curve”. Geogebra is available here. When you try and recreate the applet, don’t worry if the first three numbers appear as sliders, it will still work fine.

Also, see the message below from the Think Maths website we have enjoyed in the past:

“Matt Parker has launched Matt Parker’s Maths Puzzles! Once a week we can now look forward to a puzzle video from Matt on his Stand-Up Maths YouTube Channel.

Each week Matt will give us a puzzle and pose a question. Viewers can submit their solution to that question online to receive points and appear in a puzzle participants league table. 

Matt will be awarding hilarious virtual prizes when participants reach particular point milestones.

The first puzzle video is here. Submit your answer here: www.think-maths.co.uk/table-puzzle

We aim for puzzle videos to be released on a Wednesday afternoon UK time, with the deadline for submissions the Tuesday of the following week at 11:59pm UK time. 

Sign up to recieve an alert email when puzzle videos come out here: https://www.think-maths.co.uk/puzzles-sign-up

On Fridays we will post a solution video to the previous week’s puzzle and the updated league table on this page: www.think-maths.co.uk/maths-puzzles“

Take care everyone.

Age brainteasers

Here are a couple of age puzzles from David Pleacher’s great site. Answers are on there too.

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During a recent census, a man told the census taker that he had 3 children.
When asked their ages, he replied, “The product of their ages is 72.”
“The sum of their ages is the same as my house number.”
The census taker ran to the door and looked at the house number.
“I still can’t tell,” she complained.
“Oh, that’s right. I forgot to tell you that the oldest one likes apple pie.”
The census taker promptly wrote down the ages of the three children.
How old are they?

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Edie and Dave were talking when they saw three people coming toward them.
“I wonder how old they are,” said Edie.
Dave replied, “I know them!
The product of their ages is 2,450 and the sum of their ages is twice your age.”
“That’s all well and good,” said Edie, “but I need more information.”
“Oh yes,” said Dave.
“Well, I am older than any of the three.”
“Now, I can figure their ages,” said Edie.

How old are the three?

****

In case they were too easy here is a fiendish one to try by John H. Conway.

Last night I sat behind two wizards on a bus, and overheard the following: A: “I have a positive integral number of children, whose ages are positive integers, the sum of which is the number of this bus, while the product is my own age.” B: “How interesting! Perhaps if you told me your age and the number of your children, I could work out their individual ages?” A: “No.” B: “Aha! AT LAST I know how old you are!” Now what was the number of the bus?

Here is a paper which discusses the puzzle and solution.