All posts by Teun Spaans

About Teun Spaans

Hi, I'm a puzzle collector & designer. I have collected and designed puzzles for about 30 years, though not with great intensity. Other stuff: my blog about plants and nature my professional blog my website

Truth-speakers, Liars and Switchers



The remote island of Zwrazr in the Logico archipelago is inhabited by three types of people: Truth-speakers, Liars, and Switchers. Truth-speakers always speak the truth, Liars always lie, and Switchers alternate their sentences between a true sentence and a lie.

As you arrive on the island, a group of three natives comes to greet you. According to tradition, the group consist of one representative of each group. Luckily for you, they introduce themselves:

  • The left one says: I am a truth speaker
  • The middle one says: I am a liar
  • The one on the right says: I am a switcher

So now you know who is who, don’t you?

You can check your solutions here

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Matchsticks – hexagon


Matchsticks puzzles are over a century old, but seem to go through a revival with several apps featuring them.

1) Move 3 matches**/*****
From the figure above, move 3 matchsticks so that you have 4 same sized triangles.

2) Move 4 matches***/*****
From the figure above, move 4 matchsticks so that you have 4 same sized triangles.

You can check your solutions here and here.

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

On the isle of Uauau



On the isle of Uauau the natives speak the truth on one day and lie on the next. On his or her “truth-day”, the man or woman will always speak the truth, and on their “lie-days” they will always lie. As a furthttps://justpuzzles.wordpress.com/?p=5097&preview=trueher complication, their truth days and lie-days are not synchronized, what is a truth day for one of them can be a lie day for his neighbor, father, brother or friend.

1) Today is a truth-day for me*/*****
You meet a native who says: “Today is my truth day”. Can you conclude if he has a truth-day or not?

You can check your solutions here

2) Yesterday*/*****
On Friday you meet a native who tells you: “Thursday is one of my lie-days”. Can you conclude if the native is speaking the truth or not?

You can check your solutions here

3) Different truth-days**/*****
You meet two natives. One of them tells you:
“My friend and I have different Truth-days. Today is my friend’s lie-day.”
Does at least one of them have a lie-day?

You can check your solutions here

4) Friday(1)***/*****
You meet two natives, let’s call them A and B as their real names are hard to pronounce. A says:
(1) My friend and I have the same truth-days.
(2) Last Friday my friend had a lie-day.
Does A speak the truth?

You can check your solutions here

5) Friday(2)***/*****
You meet two natives on a Friday. For a change, let’s call them A and B, as their names are hard to remember. A says:
Yesterday I would have said that Friday is B’s truth-day.
Does B have a truth-day today?

You can check your solutions here

What comes next?


what comes next?****/*****
1, 1, 2, 5, 12, 35, 108, …

You can check both your solutions here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Nonogram


Sanders, the most innovative puzzle magazine publisher in my native Netherlands, recently published a new variation of Nonogram, also referred to as Hanjies, grid puzzles, picross or, in Dutch, Japanese Puzzles (Japanse puzzels).

It uses triangular grids instead of the customary square grids, which adds a nice touch to this puzzle type. This puzzle type is sometimes called Triddlers, and comes in two types:
(a) the triangles are the half of a square.
(b) These triangles are equilateral triangles, with 60 degrees in every corner.
The puzzles in this publication arte of the latter type, which I much prefer. A nice feature is the inclusion of a small puzzle alongside a big one on every page. Well recommended!
You may wish to try to obtain one through their webshop, I just discovered they now ship internationally.

(Apologies for not including a sample puzzle this post, I havent yet discovered good tools for making good triangular or hexagonal grids. Tips are appreciated, plz add them in the remarks section)

Bongard problem 34


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 34**/*****


You can check your solutions here

You can find more Bongard problems here and at Harry Foundalis site, and in the category ‘Bongard problems’ in the right margin of this page.

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

The same coffee


The same coffee*/*****
My wife and I visited a restaurant. When my wife found a fly in the coffee, I called the waiter, who took the cup away and returned with a fresh cup.
As the waiter walked away, my wife angrily called him back and said: “You brought me the same coffee!”

How did she know?

You can check both your solutions here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Cryptarithm: metals


In the following sums, digits have been replaced by letters. A digit was always replaced by the same letter, and every letter always represents the same digit.

Metals 1**/*****
cryptarithm-2016-12-03-metals-exercise-nr-1

Metals 2***/*****
cryptarithm-2016-12-03-metals-exercise-nr-2

You can check your solutions here and here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Matchsticks – the T


Have a look at the following figure:
matchsticks-t-2017-01-20-exercise


You can easily check that 16 matches form 5 squares.

Move 2 matches**/*****
Move 2 matches to create 4 squares

You can check your solution here

Move 3 matches**/*****
Move 3 matches to create 4 squares

You can check your solution here

Move 4 matches**/*****
Move 4 matches to create 4 squares

You can check your solution here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.

Words


On Twitter I follow several accounts, one of which is Genius Brain Teasers.

One of the type of puzzles they publish is of the type: Remove x letters from this sequence to reveal a familiar English word.

My main criticism on this puzzle type is that they tend to be fairly easy. I’m a non native speaker, and if I can solve them, most native speakers should find them even easier. Nevertheless, as I don’t recall having seen them elsewhere, I think they deserve to be mentioned here.

Let me try to give you some examples:
Hidden word 1*/*****
Remove 5 letters to reveal a familiar English word:


Hidden word 2*/*****
Remove 5 letters to reveal a familiar English word:


Hidden word 3*/*****
Remove 5 letters to reveal a familiar English word:


Here’s a small variation of my own:
Hidden words 4*/*****
Remove 4 letters to reveal a familiar English word. Then, remove 4 other letters to reveal a different English word:


Hidden words 5*/*****
Again, you find the letters of 2 words. Remove 4 letters in 2 different ways to reveal 2 familiar English words.


You can check all your solutions here

New puzzles are published at least twice a month on Friday. Solutions are published after one or more weeks. You are welcome to remark on the difficulty level of the puzzles, discuss alternate solutions, and so on. Puzzles are rated on a scale of 1 to 5 stars.