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This was their first puzzle:
Take the digits 1,2,3 up to 9 in numerical order and put either a plus sign or a minus sign or neither between the digits to make a sum that adds up to 100. For example, one way of achieving this is: 1 + 2 + 34 - 5 + 67 - 8 + 9 = 100, which uses six plusses and minuses. What is the fewest number of plusses and minuses you need to do this? Solution
A recent Emojipedia blog post has done an interesting job at trying to visualise data relating to the popularity of emojis on a particular day on a particular platform. This is clearly a complicated subject and would lead to interesting discussions in classes relating to sampling, data collection and presentation of data. The graph showing which emojis are used alone or together could be a good basis for discussing misleading graphs.
Start your collection of extension puzzles with this brainteaser. Post your answers in the comments! Correct answers will be revealed at the end of November 2017.
There are a number of mathematics books floating around online but some are clearly copyright infringements. Project Gutenberg however, is all completely above board and specialises in older books which are completely in the public domain. Of the many mathematics books in their collection, my favourite is Amusements in Mathematics by Henry Dudeney. It was published in 1917 and contains a series of short puzzles suitable for use in the classroom. Here's a typical example: I have nine counters, each bearing one of the nine digits, 1, 2, 3, 4, 5, 6, 7, 8 and 9. I arranged them on the table in two groups, as shown in the illustration, so as to form two multiplication sums, and found that both sums gave the same product. You will find that 158 multiplied by 23 is 3,634, and that 79 multiplied by 46 is also 3,634. Now, the puzzle I propose is to rearrange the counters so as to get as large a product as possible. What is the best way of placing them? Remember both groups must multiply to the same amount, and there must be three counters multiplied by two in one case, and two multiplied by two counters in the other, just as at present.
Following on from a successful training session at Brillantmont International School in 2017, the LMTN was born. It's mission is to forge links between Lausanne maths teachers and share resources. You can add comments to this blog or send ideas and resources straight to the administrator of this site, johnkennedy <at> brillantmont.ch
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AuthorJohn Kennedy Archives
September 2018
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