- Friday 09 June 2017
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An awesome example of mathemagic is the mind-reading trick based on using a set of cards to determine a secret number. A volunteer is asked to choose a secret number, and then is shown a series of cards and asked to state whether their secret number appears on the card that is shown. Based on the answers the mathemagician can determine the secret number. A set of cards for determining a secret number between one and thirty-one are shown below.
Imagine that the secret number was 9. The person would state ‘yes’ when shown card 1 and card 4. Note the numbers in the top left corners (1 and 8). Adding the numbers in the top left corner reveals the ‘secret number’. This explains how the trick is done—of more interest is why the trick works and how it may be used to stimulate the development of some mathematics. While I would not advocate the use of tricks and puzzles simply for the sake of doing them, they do provide students with the motivation to explore the mathematics behind the trick.
Dr Paul Swan has written a number of Australian Curriculum resources for R.I.C. Click on the image(s) below for more information on these resources.
