**1) 3-7=8?**^{***/*****}

Please correct the following equation by moving two matchsticks:

You can check your solutions here

New puzzles are published at least twice a month on Fridays.

**1) 3-7=8?**^{***/*****}

Please correct the following equation by moving two matchsticks:

You can check your solutions here

New puzzles are published at least twice a month on Fridays.

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Searching for puzzle apps on my android phone, I encountered “Probability puzzles” by “atorch”. Nice puzzles, although this type of puzzle never was one of my favorites and probably never will be. The app is working well, and the puzzles are varied. Well recommended.

Probability actually has its root in betting and games of chance. I was reminded of this when I was downloading the “Print and play” game Fazenda. Unfortunately the dice were missing.

In the rules of Fazenda, there are three dice. All 18 sides are either brown or blue.

**Three dice**^{**/*****}

This weeks problem is this

Suppose that the three dice are identical, and that they each have 2 brown and 4 blue sides, what is the chance that at least two brown sides come up?

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to discuss difficulty levels, variations and alternate solutions, but plz. don’t publish the solutions. The solutions will be published after one or more weeks, and yes, we know that you are smarted than any one else.

You can check your solution here

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.

After the previous puzzle you are thirsty, and the truth-speaker brings you to a bar close to the harbor. He points at a table with three people, and tells you they are a Truth-speaker, a Liar and a Switcher. He tells you the three people are called Al, Bill and Cindy.

Al says:

Bill is a Liar

Cindy is a Liar

Bill tells you:

Al is a liar

Cindy is a switcher

Cindy sips her cola and thoughtfully says:

Bill is a truth-speaker.

So, who is who?

You can check your solutions here

New puzzles are published at least twice a month on Fridays.

This week I’d like to present a new type of maze.

Somewhere among the concept of this blog is a concept about mazes, their history, their shapes and their applications. In my small library are at least two good books about mazes. But here’s a new type of maze. Smaller versions may be suitable in the class room, while this shape and size are aimed at adults.

Your task? You see the two big 7’s? Find your way from one to the other, by moving vertically or horizontally, through squares which are a multiple of 7. Sounds easy, does it?

You can check your solution here

New puzzles are published at least twice a month on Fridays. Solutions are published after one or more weeks. You are welcome to discuss difficulty levels, variations and alternate solutions, but plz. don’t publish the solutions.

**In the restaurant**^{***/*****}

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.

In a restaurant, a group of natives are sitting at a circular table.

They take turns to say: the person to my left is a Switcher.

After that, they take turns, starting with the same person, to say: the person to my left is a Liar

What can you say about their type? How many are Truth-speakers? How many are Switchers? How many of them are Liars?

You can check your solution here

New puzzles are published at least twice a month on Friday. 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.

Today we have “special forces”, such as the SAS in the UK, the Russian Spetsnaz, and the USA Rangers and Seals. In the middle ages these special forces had a name that still rings today: knights. The link between them and todays puzzle is very thin: the knight got a place in western chess, and todays puzzle uses the move of the knight on the chessboard.

In the series on new magazine format puzzles, I published a post on a new word format puzzle I encountered in the free newspaper metro in my native Netherlands.

In it, you have a 3×3 grid, the center of which is empty, while the outer edge is filled with letters. The letters form a word, and consecutive letters are always a knights jump (knight in chess) apart. Example:

For those who don’t know how a knight in chess moves: move one horizontally or vertically, followed by a diagonal move away from the starting square.

A knight on the square marked “K” may move to any square marked “X”.

My main criticism is that the puzzles as published by Metro are too easy to solve.

Today it occurred to me that the size of the board can be increased, and the size altered, to increase the difficulty of the puzzles.

That increased size raises the difficulty level of the puzzle is easy to understand: a larger size does not only give more starting positions, but also more possible moves on subsequent moves.

Another way to increase the difficulty is by not using single letters – the human mind in the western world is used to work with them – but digrams (two letter combinations) or trigrams (three letter combinations).

**Proverb split into digrams**^{***/*****}

**Proverb split into trigrams**^{***/*****}

A new puzzle is published at least twice a month. I welcome your comments below, but please do not spoil the fun for next visitors by listing your solutions. Solutions are published one or more weeks later. You can find more puzzles with words by following the link to the right.

You can check your solutions here

What do you read when you superposition these three figures?

You can check your solution here

New puzzles are published twice a month on Fridays. Solutions are revealed one or more weeks later.

This puzzle was inspired by the “100 doors” app, and by the Dutch translation of 1000 casse-tete et enigmas by Piere Berloquin.

What is the smallest number that has a remainder of 2 when divided by 14, 18 and 32?

You can check your solution here

New puzzles are published at least twice a month on Fridays.

Dominosas are puzzles where the dominoes have been shuffled and turned face up. All the numbers are given, but the borders between the dominoes are not given – these have to be solved by the reader.

I used to publish quarterly on them at my site domino plaza.

Usually a 6×6 set of dominoes is used, though larger or smaller sets can be used.

Here are two examples:

**1) The christmas bauble**^{**/*****}

You can check your solution here

**3) Solving strategies**

**a) Counts**

Make a count of how often all combinations appear. To do so, list all dominoes and how often they appear in the puzzle:

0-0: 2

1-0: 3

1-1: 5

2-0: 2

2-1: 1

2-2: 3

and so on.

This will give you the position of 2-1. Mark the borders on the printed puzzle.

**b) Cross off deleted connections**

Continuing the above example, it is easy to jump to a conclusion about 3-3, but before that we have some bookkeeping to do. Identifying the domino severed a number of links. In our example the severed links are the 3-1, 6-1, 2-0, and 5-2. When we update our list above for these severed links, we find that the number of 2-0 combinations is now reduced to 1, giving another domino.

**c) Unique positions.**

In this diagram, it is easy to see that in the top left position, only-the 3-3 is possible.

**d) Block impossible links**

Identifying the 3-3 domino blocks the link between all other 3-3 combinations:

This in turn, will in some situations trigger another situation like in step c)

New puzzles are published at least twice a month on Fridays. Solutions are usually published after one or more weeks.

External links:

https://www.puzzle-dominosa.com/ – play them online

https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/dominosa.html – another online game site

http://medmunds.github.io/puzzles/dominosa.html – 3rd in line play

https://play.google.com/store/apps/details?id=com.oxothuk.dominosa – android app

http://www.mathematica-journal.com/2014/10/three-ways-to-solve-domino-grids/ – three ways to solve them.

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 colours**^{**/*****}

You can check your solution 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.

Next month I intend to publish a Christmas special.