Author: xi'an

Le Monde puzzle [#1073]

And here is Le Monde mathematical puzzle  last competition problem Find the number of integers such that their 15 digits are all between 1,2,3,4, and the absolute difference between two...continue reading.

Le Monde puzzle [#1072]

The penultimate Le Monde mathematical puzzle  competition problem is once again anti-climactic and not worth its points: For the figure below [not the original one!], describing two (blue) half-circles intersecting...continue reading.

Le Monde puzzle [#1070]

Rewording Le Monde mathematical puzzle  fifth competition problem For the 3×3 tables below, what are the minimal number of steps to move from left to rights when the yellow tokens...continue reading.

Le Monde puzzle [#1066]

A purely (?) algorithmic Le Monde mathematical puzzle For the table below, what is the minimal number of steps required to reach equal entries when each step consists in adding...continue reading.

Le Monde puzzle [#1068]

And here is the third Le Monde mathematical puzzle  open for competition: Consider for this puzzle only integers with no zero digits. Among these an integer x=a¹a²a³… is refined if...continue reading.

Le Monde puzzle [#1066]

Recalling Le Monde mathematical puzzle  first competition problem For the X table below, what are the minimal number of lights that are on (green) to reach the minimal and maximal...continue reading.

riddles on a line [#2]

A second Riddle(r), with a puzzle related with the integer set Ð={,12,3,…,N}, in that it summarises as Given a random walk on Ð, starting at the middle N/2, with both...continue reading.

Le Monde puzzle [#1650]

A penultimate Le Monde mathematical puzzle  before the new competition starts [again!] For a game opposing 40 players over 12 questions, anyone answering correctly a question gets as reward the...continue reading.

riddles on a line

In the Riddler of August 18, two riddles connected with the integer set Ð={2,3,…,10}: Given a permutation of Ð, what is the probability that the most likely variation (up or...continue reading.

Le Monde puzzle [#1063]

A simple (summertime?!) arithmetic Le Monde mathematical puzzle A “powerful integer” is such that all its prime divisors are at least with multiplicity 2. Are there two powerful integers in...continue reading.

Le Monde puzzle [#1062]

A simple Le Monde mathematical puzzle none too geometric: Find square triangles which sides are all integers and which surface is its perimeter. Extend to non-square rectangles. No visible difficulty...continue reading.

Hamiltonian tails

“We demonstrate HMC’s sensitivity to these parameters by sampling from a bivariate Gaussian with correlation coefficient 0.99. We consider three settings (ε,L) = {(0.16; 40); (0.16; 50); (0.15; 50)}” Ziyu...continue reading.

seven digit addition

Another quick riddle from the riddler: solve the equation EXMREEK + EHKREKK = ?K?H?X?E which involves every digit between 0 and 9. While the puzzle can be unravelled by considering...continue reading.

Le Monde puzzle [#1051]

A combinatoric Le Monde mathematical puzzle of limited size: When the only allowed move is to switch two balls from adjacent boxes, what is the minimal number of moves to...continue reading.

Le Monde puzzle [#1045]

An minor arithmetic Le Monde mathematical puzzle: Take a sequence of 16  integers with 4 digits each, separated by 2,  such that it contains a perfect square and its sum...continue reading.

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