1) Move 6 matches**
Consider the following figure:
Now move 6 matches so that you have 4 squares.
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 three stars.
The September issue of the Dutch magazine Quest came with a small origami puzzle booklet. It contains 8 puzzles. The puzzle in each case is to fold a square piece of paper, such as depicted below, in such a way that one side is black and the other side is white.
There is a book published by “The Incredible Company“. You can freely download a free pdf with 5 puzzles from there site. The book does not seem to mention an author, though I suspect the author is Jérôme Morin-Drouin. Play testers were two people named Caro and Felix.
To solve the puzzles below, print them, cut them and fold them such that the result is a sqiuare, white on one side and black on the other.
Puzzle 1*/*****
Puzzle 2*/*****
Puzzle 3*/*****
No solutions will be given.
Credits go to Quest for pointing out this puzzle type, to the incredible company for coming up with the idea and to my daughter Margreet for puzzle number 2 above. NUmbers 1 and 3 are my own work.
Cryptarithm*
In the following cryptarithm, replace every letter with a digit. The same letter always represents the same digit and identical digits have always been replaced by the same letter:
A new puzzle is published every 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 three stars.
You can check 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 three stars.
1) The logicians club**/*****
Yesterday I visited a club of logicians. It’s a very special club, only trained logicians are admitted as members. During the club meetings, all members are required to speak the truth the entire evening, or to lie the entire evening. All members were seated around the circular table, truth tellers and liars alternating. I was not a member and watched from a distance. The president of the club welcomed all the members, and especially me as a guest.
He also explained some more rules which I admit I have quite forgotten. One part of the evening consisted of questions the members asked about the rules, while another topic were the finances.
At the end of the meeting, I asked the president how many members this club had. He happily told me that all 20 members had been present. When I was about to leave, I suddenly realized that the president himself need be trusted, and asked the secretary if the president had spoken the truth.
“Oh no!” the secretary exclaimed. “You should not believe the president, tonight he was a notorious liar! At this evening’s meeting, all 21 members were present!”
Whom should I believe? And why?
The puzzle above comes from “Denken als Spiel”, by Ernst Hochkeppel, one of the earliest puzzle books I obtained.
You can check your solutions here
2) The party***/*****
Once there was a party where everybody with 100 people. Everybody shook hands with a number (some or all) of other people. Everybody present was either a liar (someone who always lies) or a Truthteller (someone who always speaks the truth).
When leaving the party, everybody was asked with how many Truthtellers he or she had shaken hands with. All answers 0, 1, 2, etc till 99 occurred exactly once.
How many Truthtellers were at the party?
This puzzle can also be watched as a video by Mindyourdecisions on youtube.
You can check 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 three stars.
Which day of the week is it?**/*****
Inspector Simon Mart opened his eyes. The lights hurt and he quickly closed them again. Slowly his memories returned. He had landed on the island of Odders and Eveners in the Logico archipelago. Like all islands in this archipelago, the inhabitants had strange habits when it came to speaking the truth and when lying.
The Odders spoke the truth on the odd days of the week: On Sunday, Tuesday, Thursday, and Saturday, and lied on the other days.
The Eveners spoke the truth on the even days of the week, on Monday, Wednesday, and Friday, and lied on the other days.
On the evening of his arrival, he had taken part in the arrest of some smugglers, and he had been beaten unconscious with a coconut. How long would he have been unconscious?
A nurse entered the room of the hospital and he heard a sweet voice asking how he felt. He quickly opened his eyes and saw that it was an indigenous inhabitant of the island.
“What day is it?” he asked.
“Tomorrow I will speak the truth,” she answered cryptically, in the same reassuring tone that some mothers use against their toddlers. Just before he lost conscious again, he realized that the nurse had actually answered his question.
What day of the week was it?
You can check your solutions here
There are many beautiful puzzles with coins. I don’t mean those which have to do with the value of the coins, but with the puzzles in which you have to move coins around. Neither do I want to discuss the puzzles which are about arranging coins in a straight line. These are often represented as planting trees in a row, and I discussed them here.
While on holiday in France this summer, I bought two puzzle booklets in the ‘aires’, the road stops with a restaurant, a gasoline station, a toilet and some more. One of them, ‘Best of jeux de vacances, 700 jeux’ by Pascal Naud, contained at least two of them, both classics, so I can reproduce them here without encountering copyright problems.
You can check your solutions here
You can check your solutions here
Many similar (and much more difficult) problems can be found on youtube.
At the beginning of the summer I was asked to become one of the elders in our church. It unfortunately means that I am not able to keep up the rate of a puzzle a week. Having a fair collection of posts in stock, I was able to keep posting puzzles weekly. But I’ve about run out of puzzles in stock. So be prepared there will be 2 puzzles a month from now on till the end of the year.
You are still welcome to comment on puzzles here, or to buy my book.
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 8**/*****
You can check your solutions here
You can find more Bongard problems here and at Harry Foundalis site, and I intend to publish more problems in the future.
A new puzzle is published every 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 three stars.
A few weeks ago I wrote about a Japanese Tangram from 1742, pre-dating the well known Chinese Tangram, and gave some classical figures with the 7 pieces. This week I’d like to present some figures wit the theme: In and around the water.
Again I’d like to thank my wife Jos and our daughter Margreet for coming up with these figures.
You can check your solutions here
A new puzzle is published every Friday. Solutions are published after one or more weeks. You are welcome to discuss the puzzles, their difficulty level, originality and much more.
Use 3 3’s to make exactly 20.
Hint: USA inhabitants have it easier.
You can check your solutions here
A new puzzle is published every Friday.
Rearrange these matchsticks so that you have 3 squares. Can you find both solutions?
You can check your solution here
The solution will be published after a few weeks
justpuzzles 