Sign In | Starter Of The Day | Tablesmaster | Fun Maths | Maths Map | Topics | More

Happy New Year. I hope that 2018 proves to be a good, positive number for you and that you, and your pupils, achieve all that you want during the next twelve months. If the Roman numeral in the title caught your eye you may like the Roman Numerals Quiz.

This month's puzzle is taken from the excellent book I have been reading during the holiday called "Can You Solve My Problems" by Alex Bellos. I have just read the problem called "The Shrivelled Spuds" which I present to you here:

A pile of potatoes weighing 100kg is put in the sun. Ninety nine per cent of the weight of the potatoes is made up of water. After a day some of the water evaporates., with the result that 98 per cent of the weight of the potatoes is now made up of water. What's the new weight of the potatoes?

The answer is at the end of this newsletter.

I thoroughly recommend the book as not only is it an ordered collection of intriguing puzzles but it also has an extensive solution section in which Alex provides insights, history and worked solutions for the puzzles. The chapters are Logic Problems, Geometry Problems, Practical Problems, Problems with Props and Problems for Purists. Here is a link to buy the book from Amazon.

Last month the website was added to and updated as usual but the one new activity I would like draw your attention to is the Area Wall Puzzles. The core concept is a puzzle called Shikaku, an original Nikoli puzzle and though the Transum version refers to area, the activity requires the ability to consider factor pairs of small numbers.

In the process of creating and testing the puzzles I realised how addictive this type of problem solving is. Just like Sudoku solving you will develop strategies as you become more proficient and experience a nice sense of accomplishment when the wall is completely coloured in.

Another new activity is called "Equation of a Line Through Points". It is a four level exercise requiring users to match the equations of the straight line graphs to the clues about gradients and points. This exercise could be attempted after some of the more basic "y=mx+c" activities have been mastered.

Finally, my answer to this month's puzzle is 50kg

I found this by first realising that if 99% of the original pile is water then 1% must be other, dry matter.

1% of 100kg is 1kg.

Let the weight of the potatoes after the drying be x.

0.98x + 1 = x

1 = 0.02x

x = 50

That's all for now

John

P.S. You have to be odd if you want to be Number One.

Do you have any comments? It is always useful to receive feedback on this newsletter and the resources on this website so that they can be made even more useful for those learning Mathematics anywhere in the world. Click here to enter your comments.