Math game: controversy at the cash register

Math game controversy at the cash register

Do you have to be an expert at mental arithmetic or write down all the prices to check a bill at the supermarket?

Maxime bought two pens, € 1.20 each, eight identical notebooks and twelve sheets of also identical drawing paper. While going to the cash register, the hostess announces to him: ” vsa will be € 16.50 ”. Maxime does not remember the price of each of the notebooks and drawing sheets but replies: “ It is not possible ! ” Why ?

Responnse :

This total is not possible, regardless of the unit prices of the last two items if they are a number whole pennies. In fact, the eight notebooks and the twelve sheets would then cost 1,410 centimes, which is not divisible by four.

Learn more about Hervé Lehning

Normalian and agrégé in mathematics, Hervé Lehning taught his discipline for more than forty years. Crazy about cryptography, member of the Association of Cipher and Information Security Reservists, he in particular unraveled the secrets of Henry II’s cipher box.

Buy the book
Click to buy the book

Also to discover: The universe of secret codes from Antiquity to the Internet published in 2012 by Ixelles.

Interested in what you just read?

Subscribe to the newsletter Fun math : every week, Futura deals with a mathematical question for the pleasure of 7 to 77 year olds. All our newsletters