Monthly Archives: February 2016

Letterboggle (2)


In January 2014, I published a one puzzle blogpost on Letterboggle. Going through old notebooks, I discovered some more of these puzzles.

Let me restate the rules:
* All 26 letters of the alphabet have been used exactly once;
* two letters which are consecutive in the alphabet are always adjacent either horizontally, vertically or diagonally. Hence the alphabet forms a kind of snake throughout the firgure;
* The letter A does not need to be adjacent to the letter Z;
* A letter in the margin is present in the same row (if margin letter is adjacent to a row), in the same column (if the margin letter is on top or bottom of a column) or in the same diagonal (if the mnargin letter is in one of the corners);

Letterboggle (1)*
Letterboggle 2016-02-03 nr 1 exercise

Letterboggle (2)*
Letterboggle 2016-02-03 nr 2 exercise

Letterboggle (3)**
Letterboggle 2016-02-03 nr 3 exercise

Note that not all border fields contain a clue. This is on purpose.
Personally I would find alphabet snake a better name, but

You can check your solution here, here and here.

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The spy and the sentry


Castle DSC_0048A spy wanted to enter a castle, but this castle was guarded by a sentry. Only those who knew the password, were allowed to enter. The spy hid himself in the bushes near the guardhouse of the sentry, so that he could overhear the password.
The baker approached, and the sentry called:
‘If I say 12, what do you reply?’
‘6’
‘You may pass.’
The smith approached, and the sentry called:
‘If I say 6, what do you reply?’
‘3’
‘You may pass.’
The spy concluded: ‘I know enough’
With a long detour he went back, disguised himself as a grocer and approached the sentry. The sentry called:
‘If I say 4, what do you reply?’
‘2’
The spy was taken prisoner.
What should he have replied?

I would like to thank our daughter Margreet for passing on this nice problem, which she heard from Professor Jochem Thijs. Alas he did not reply to my question if he invented this puzzle or not. If he is not the inventor, and someone knows the original source, I would be grateful.

You can check your solution here

You are welcome to remark on the puzzle: its wording, style, level of difficulty. I love to read your solution times. Please do not spoil the fun for others by listing the solution.

Bongard problem (4)


The Russian scientist M.M. Bongard published a book in 1967 that contains 100 problems. Each problem consists of 12 small boxes: six boxes on the left and six on the right. Each of the six boxes on the left conform to a certain rule. Each and every box on the right contradicts this rule. Your task, of course, is to figure out the rule.

Bongard problem 2015-11-20 exercise

You can check your solutions here


You can find more Bongard problems at Harry Foundalis site, and I intend to publish more problems in the future.

A new puzzle is posted every friday. You are welcome to comment on the puzzles. Solutions are added at the bottom of a puzzle after one or more weeks.