As December has begun I hope you don’t consider it too early for me to wish you a Merry Christmas. As usual this newsletter will begin with a puzzle of the month. A slightly more difficult puzzle this month that could keep you thinking right through the holiday.

Young Noel Stocking checked his bank account to see how much money he had to buy Christmas presents. When he recorded the balance he wrote down the number of pence for pounds and the number of pounds for pence. A transposition error. “Wahoo” he exclaimed “I’m rich!”

While in this good mood Noel promised 50p to his younger sister Merry. He adjusted his record accordingly which now turns out to be exactly double the amount in the bank.

How much does Noel have in the bank?

Many of the activities on the website have been updated during November and, in preparation for the festive season, the Christmaths collection has been brightly polished. Here are my favourites:

Christmas Ornaments: A puzzle which can be solved online or by using the printable boards so the task can be done in a very practical way with real Christmas ornaments. Problem solving, trial and improvement and logic all wrapped up in one for Christmas.

Christmas Eve Snow: This is a letters-replace-digits puzzle which comes with clues and, if you scroll down to the bottom of the page, a step-by-step guide for solving this kind of puzzle.

Christmas Tables: This is the special Starter for Christmas Day. When I first saw the Betty Edwards drawing I was amazed that the sense of perspective is so powerful. You will need Flash to view the animation.

Cracker Joke: This is a basic numeracy activity where answers to simple calculations are converted to letters to spell out a maths joke. Each time the page loads the calculations change. You can change the joke too.

The Power of Christmas: This Starter works well with Year 11 and Year 12 pupils as it tests their understanding of indices. Finding one solution is fine but the real challenge is to find all four solutions.

The Twelve Days of Christmas: This is a well-worn and time-honoured problem that’s certainly doesn’t deteriorate with age. I particularly like the solution as sung by Natalie Cole.

Christmas Tree Trim: This is just one of the activities on the Transum website that allows pupils to demonstrate their systematic listing skills. There are eight levels of difficulty and a trophy available for each level.

The links to all of these activities (and more) can be found on the Christmaths page. The last week of term is a great time to do some out-of-the-ordinary mathematics with your pupils and there are plenty of ideas on that page. In my experience some of the end-of-term, fun maths has turned out to be the most memorable and enjoyable learning my pupils did all year!

Have your pupils encountered the binary system? There is a visual aid you can use called Binary Lights to demonstrate how binary works. The reason I mention this is that recently I heard a nice idea about counting on your fingers. It’s common knowledge that you can count to ten with the help of fingers and thumbs but if you use binary you can count up to over 1000! Scroll down the Binary Lights page to see a video demonstration.

The answer to this month’s puzzle is £16.33. I found this answer with the aid of a spreadsheet. Please let me know if you have another way of finding this answer.

That’s all for this month

Enjoy the holiday

John

Q. How is an artificial Christmas tree like the square root of minus nine?

A: Neither has real roots!