Math game: controversy at checkout

Do you have to be an ace of mental math or write down all the prices to check an addition to the supermarket?

Maxime bought two pens, € 1.20 each, eight identical notebooks and twelve sheets of drawing paper also identical. Going to the cashier, the hostess announces: vswill make € 16.50 ”. Maxime does not remember the price of each of the notebooks and drawing sheets but replies: ” It is not possible ! ” Why ?

Reply :

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

Find out more about Hervé Lehning

A normalien and an aggregator of mathematics, Hervé Lehning has taught his discipline for some forty years. Crazy about cryptography, a member of the Association of Reservists of the cipher and information security, he in particular has uncovered the secrets of Henri II’s encryption box.

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