Author: Emily Fleming

Gabriel wrote the numbers 1-9 in a 3×3 grid.

He then multiplied together all the numbers in each row and wrote the resulting product next to that row.
He also multiplied the numbers in each
column together, and wrote the product
under that column.
He then rubbed out the numbers 1-9.

Can you work out where Gabriel placed the numbers 1-9?

Did you have more information than you needed?

This puzzle comes directly from this NRich page, with the pdf of the problem available here.

Today we looked at this “playable post on the nature of society”. It is a great activity to make you think about how you can positively contribute to society becoming less segregated.

We tried to work out the maths behind the applet. Where does 95% come from in the screenshot from above?? In the javascript for the applet you can see that a measure of “sameness” is used which involves the fraction of neighbours that are the same as you. Can you create/recreate the algorithm used to find the 95%?

91 card game

This card game can be played with two or more players. The goal of the game is to collect the most number of points possible. You do this by biding on the diamonds, using your cards.

The game starts with each player having one complete suit, for instance, one player could have the spades. You can use more than one pack if there are more than three players.

The diamonds are mixed up and placed in the middle. These diamonds are turned over one by one and each player throws a card depending on the value of the diamond card. The values for each card are as follows:

King – 13   Queen – 12   Jack – 11 and the rest of the cards follow as such, Ace being worth 1 point.

The player who’s card has the highest value collects the diamond card. In the picture above, the person who played the King of Clubs would win the Jack of Diamonds.

If there is a tie and two or more people play cards of the same value, then another diamond is added to the middle and all the players bid again for these cards. If the final card played by each player is a tie then no one wins the diamonds in the middle.

The player who wins is the player who collects the most points out of the 91 available after all cards have been played.

Can you find a winning strategy to be able to collect the most points every time?

Another great puzzle from MathPickle … can you find the winning starting position?  What happens somewhere between 20 and 30?

Polypad can be used to display some ideas on the computer, here is a screenshot of one of our combinations:

Taxicab geometry is a form of geometry, where the distance between two points A and B is not the length of the line segment AB but the sum of the shortest horizontal and vertical distances between the two points. Example:

The first challenge is to try to find what a midpoint would be in taxicab geometry. Here is an example to help:

Since the distance between A to the midpoint is the same as the distance between the point B and the midpoint, the midpoint is at the same distance from A and B. Can you spot any more midpoints, if there are any? Can you pick two different points that do not have a midpoint?

The second task is to find what a perpendicular bisector looks like on taxicab geometry.

The third task is to try to draw a circle in the taxicab geometry.

Next, try to draw an equilateral triangle and a rhombus.

If you can do all that, try to draw other geometrical shapes you know on taxicab geometry and post them in the comments.

For more info have a look here.

This week we explored a brilliant puzzle on MathPickle.

The link above will send you a series of slides explaining the puzzle, and here is a the first page of trampoline puzzles to try.

A cryptarithm is a type of mathematical puzzle in which the digits in numerical calculations are replaced by letters of the alphabet.

Alphametics are cryptarithms in which letters form meaningful words, often in meaningful phrases. There are only a few simple rules for these puzzles:

1. The same letter always stands for the same digit, and the same digit is always represented by the same letter. So if a P stands for a 2, every P in the puzzle is a 2. If a 3 is represented by a K, every 3 in the puzzle will be a K.

2.The digit zero is not allowed to appear as the left-most digit in any of the numbers in the puzzle. For example, if the word FOOD represents an addend in a puzzle, the F may not be a zero.

3.Most alphametics have unique solutions (there is only one possible answer).

One of our favourite websites is brilliant.org, so today we spent time on it solving different puzzles. You have to register an account, but then you have access to great mathematics and other science questions.

Here is one of the puzzles we worked on: