This week's maths problem

Problem of the week

exercice de maths de la semaine, math problem of the week, problema di matematica della settimana, सप्ताह के गणित समस्या, математическую задачу недели, Ejercicio de matemáticas semanal, 今週の数学問題, בעיה מתמטית של השבוע, مشكلة الرياضيات الأسبوع, 这个周的数学问题, Haftanın matematik problemi, temporäre Problem vun der Woch, μαθηματικό πρόβλημα της εβδομάδας, math tatizo la wiki,

On Friday of each week we will post a new maths challenge.
You may submit your solution by the following Thursday.
Each problem contains two different levels of difficulty. You will be awarded from 2 to 12 points for a full answer.
Each series contains 12 problems before the stage winner is determined.
Your score will be published here.

In each series we will give away 3 books as prices. The prices will be drawn by lot among the best ten participants of the series. The books are kindly sponsored by Buchdienst Rattei of Chemnitz.

Suggestions for problems are welcome.

Deadline is 2nd of May 2019.

German version - Italian version - French version - Spanish version


Series 51

problem 603

“In an last year’s issue of the “Wurzel” mathematical magazine → ← I read something about a special kind of sorting problem. I have reconstructed this with some coloured cuboids.”
“As I see the cuboids are all of different size. I guess they have to be stacked from big to small.”
“That’s right. To do this I have a very thin piece of wood, that I can insert between any two cuboids an so turn around whatever is on top of this slat. When you look at the three depicted possibilities this means that that I don’t have to do a thing about the first stack. The two other stacks can each be turned in one go. I just have to insert the slat under the red cuboid.”
“So it’s allowed to turn a complete stack?” Bernd asked.
“Yes”, his sister answereed.


Here you can see five cuboids of different sizes (A>B>C>D>E). How many different ways are there to stack them? How many of these stacks can be turned into a correct stack in one go? - (2+2 blue points)
How many moves z do you need at most to sort a stack of n cuboids of different size? (Some assume z<=2n-3 for n>1, but is there proof?) - 4 red points.
Another red point is awarded for a stack of five cuboids (n=5) that can be sorted in exactly 5 moves.

Solving the picture-puzzle will get you two extra blue points, provided you also got points doing the regular maths problem. The rule for each picture puzzle is: Each icon represents one digit, same icons, same digits, different icons, different digits.  ©HRGauern[at]

603 Paprika


Send your solutions to Diese E-Mail-Adresse ist vor Spambots geschützt! Zur Anzeige muss JavaScript eingeschaltet sein!, if your answer contains attachments.

For text versions you can also use this form

--> here <--

Please give your full name so your points can be added to the score. If you would like to receive our weekly maths problem automatically you can

--> subscribe to our newsletter <-- .

Presently this newsletter is received by more than 1900 subscibers.

You can also send a paper copy of your solution as long as it is postmarked on or before the deadline.
Thomas Jahre
Stollberger Strasse 25
09119 Chemnitz


post address:

Thomas Jahre
Chemnitzer Schulmodell
Stollberger Straße 25
09119 Chemnitz
QR-Code for this site


0 #4 Jerry 2018-05-09 20:16
I'm gone to inform my little brother, that he should also go to
see this weblog on regular basis to obtain updated from
most up-to-date reports.
0 #3 unblocked games 2017-09-25 06:37
It is not my first time to pay a visit this web page, i am browsing this website dailly and
obtain good information from here every day.
0 #2 Quentin 2017-08-20 14:31
Hey Mike, got a question for you concerning my
+3 #1 Cora 2014-11-13 23:03
Hi therde to all, the contents existing at this site are truly remarkable for people knowledge, well, keep up the
nice woek fellows.

Kommentar schreiben