# Questions tagged [open-ended]

OPEN-ENDED PUZZLES ARE NO LONGER IN SCOPE. Used when no answer can be guaranteed to be the last, best one. If a puzzle instead has a provably optimal solution, tag with [optimization].

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### Four fours to get $\pi$

Four fours is a famous puzzle (made trivial with logarithms). For this puzzle, we take inspiration from Glen O's challenge from a few years back. The rules here are slightly different, but the goal is ...
175 views

What is the shortest string of letters that yields no results in a Google search? When answering, please use the NATO alphabet in order to prevent the string from becoming a search result. Scoring: ...
6k views

### There are polygons with only right angles which have an odd number of corners

One of the interesting myths about a certain building in our university is that it has 13 corners. One way to dismiss this claim is to point out that a polygon with right angles must have an even ...
226 views

### A sentence with all numbers [closed]

Crazy thought. Can you make an (grammatically correct) english sentence using english words which are all numbers? Each word in that sentence must represent a number. I am expecting a minimum 6 ...
132 views

### What is the Longest Meaningful Sentence U can make Using single letters only? [closed]

Some Examples: I C U. S I M A B.
1k views

### Pulling Apart a Jigsaw Puzzle

Assume you have a jigsaw puzzle that is also a tessellation. This means every piece has an identical shape and can be assembled into a 2D pattern that fills the plane with no gaps. Such a jigsaw ...
924 views

### Dreadful Dastardly Diseases, or Always Atrocious Ailments [closed]

So the other day, I was in a pharmacy and I saw that they had a "cold 'n' cough" medicine. The alliteration caught my eye, and I wondered it would be possible to create alliterative names with other ...
1k views

### From jafe to El-Guest

Largely inspired by From Puzzling to StackExchange by CodeNewbie From jafe to El-Guest jafe > cafe > cate > cete > cet > get > gest > egest > e gest > e guest > el guest Rules: In any move, you ...
764 views

### Masyu puzzles with many circles

The rules of Masyu: Make a single loop with lines passing through the centers of cells, horizontally or vertically. The loop never crosses itself, branches off, or goes through the same cell twice. ...
2k views

### Second-rate spelling

Find the longest word which can be spelled with the second letters of a group words in alphabetical order. An example with incomprehensible (16 letters): a...
360 views

### Breaking Balance (Part A)

If we assume the classic balance puzzle (Twelve balls and a scale) is phrased like this: You have 12 coins that are identical except for one counterfeit that is heavier or lighter. Can you use a ...
875 views

### Peaceful Encampments

This math puzzle is due to Donald Knuth (as far as I know; maybe he got it from someone else) circa 2014. Consider a plain represented by the unit square. On this plain we want to “peacefully ...
152 views

### What's the most triangles you can make with 4, 5 or 6 straight lines?

All the triangles can stick together. The triangles counted is the independent triangles, triangles made up of two shapes, a triangle made up from 3 shapes, or the outline of the shape consisting of 4,...
1k views

### Three coins for the fair king [duplicate]

Based on the question Eight coins for the fair king: I saw a comment saying "There isn't a good solution known even with three coins in all cases". So the challenge here is to try to solve ...
168 views

### Heaven or Hell? [closed]

To decide whether you go to heaven or hell, your life is put on the balance. All depends on which way it tips. John dies and waits in line to have his life weighed. Eventually he reaches St Peter who ...
136 views

### A construction toy for children [closed]

Alice has an idea for a construction toy made from plastic. Each building block is in the shape of an uppercase letter of the alphabet. No other characters are to be used. Children will ...
181 views

### Wicked Winding Words!

What is the highest number $n$ of $n$-letter words can you find that share this property? i.e. highest number $n$ that you can find (not found on any other sites). I will accept the answer with the ...
714 views

### What is the longest word that can be made out of all the scrabble tiles?

What is the longest word that can be made out of all the Scrabble tiles? If you didn’t know, there are 100 tiles when you play Scrabble. I was wondering what was the longest word you could make out ...
328 views

### Moans to Rocky in 4 moves?

In his novel A Case of Need, one of Michael Crichton's characters claims that the classic word‑ladder‡ "MOANS to ROCKY" can be made in 4 moves (5 lines total). But the book does not ...
3k views

### A Tic-Tac-Toe type game

I found this interesting game with no name: You have a 1x11 grid, like this. The way you play is similar to Tic-Tac-Toe (aka Noughts and Crosses). Players take turns to place Xs and Os on the grid, ...
733 views

### Make a sentence with the most different uses of the same word [closed]

Background I recently stumbled across the following grammatically correct sentence: Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo. This sentence relies on the fact that the ...
279 views

### Longest autological loop?

A word is said to be autological if it describes itself. This can be a property of both nouns and adjectives; for example, "noun" is a noun and "pentasyllabic" is pentasyllabic. We can also construct ...
368 views

### Make me a room-filling pattern! [closed]

So I need a new knitting pattern, but I figured this might be a nice puzzle. I'm looking for a pixelated 2D-shape that can be used in a room-filling pattern (rotation and flipping allowed). The ...
739 views

### Improve my 3D puzzle

3D View of one solutions http://autode.sk/2Dg4FWx I designed a 4x4x4 soma cube in AutoCad and then built it with wood cubes. There are twelve pentacubes and one tetracube. Each piece is unique and if ...
324 views

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### Challenge : Create a star shaped crosswords (Smaller numbers of distinct letters wins !)

Rules: Create a star-shaped crossword using 6 letters English words. Clues for the crossword is not needed. Use common English words. Direction for diagonals is TOP to DOWN. Direction for Horizontal ...
7k views

### Playing “Guess a Number” with myself

I want to play a game where one person thinks of a number and the other tries to guess it, but I want to play this game by myself. The puzzle is to come up with a way to play this game. Rules (have ...
764 views

### Forced selfmate in n-moves

I assume most people on PSE know a bit of chess With white to move, this is checkmate (1. Qb7#): That's boring. Let's try something more interesting. With black to move, black can FORCE white to ...
272 views

### Any twelve year-old can answer this question [closed]

Come up with a question between five and ten words long with an answer that contains more than three times as many unique words as the question, does not contain any of the question words, and does ...
487 views

### Infinitely simple polygon solipsism

Solipsism — The self is all that can be known to exist. Above is a simple polygonal region divided into infinitely many different-...
385 views

### Unreflected infinitely simple polygon reflexivity

(This was retrofitted to more tightly match a surprise solution and to allow for another puzzle with the original intent.)                   &...
776 views

### Prime Circuit Optimisation

It's logic gates time! You are only allowed to use NOT, OR, AND, XOR gates, accepting 1,2,2,2 inputs respectively. PART ONE You must build a circuit with $n$ inputs, and 1 output. The output must be ...
259 views

### She Lia Squared: Our daughter asked, “How many words can it make?”

For puzzle experts out there I'm certain this will seem trivial. Our daughter recently conned my wife and I into purchasing interlocking foam squares for her bedroom floor. On each square is a ...
435 views

Consider the following grid of streets with roadblocks: If you are facing in the direction of the arrow and want to get to the dot, the highlighted path is the shortest: This traces out an L. Let'...
246 views

### The Autonumerigram Challenge [duplicate]

Some phrases both refer to a number, n, and are comprised of n alphabetic characters. I call any such phrase an autonumerigram. For example, four has 4 letters seven plus seven has 14 letters ...
548 views

### KenKen Zen: A journey begins

Let us shy away from the materialistic opulence of 361- cell KenKen layouts (−9 to +9, squared).  Let us contemplate a modest KenKen journey, unburdened by gratuitously ...
689 views

### Building the ideal Scrabble dice set

This is a genuine question and I don't know the "correct" answer to this. I'm also of two minds if it is really on-topic on the site. Finding the answer is surely "a puzzle" (if ...
310 views

### A Stranger (Chess Sliding Puzzle)

A suspicious stranger lurks in the village. Deal with him before escorting the King to the luxurious safety of h8. White is first to move. Only legal chess moves are allowed. Pawns are not promoted ...
416 views

### Pool of Pawns (Chess Sliding Puzzle)

The King has tired of watching the Queen swim in the Pool of Pawns. Help him return to his palace on h8 using as few moves as possible. Only legal chess moves are allowed. Pawns are not promoted on ...
1k views

### Rook River (Chess Sliding Puzzle)

The absent-minded king has gotten himself lost. Help him return to his palace on h8 using as few moves as possible. Only legal chess moves are allowed. Pawns are not promoted on the final rank. You ...
Let's call De Bruijn n-phrase a sequence $S$ of n words $W_1 W_2 W_3... W_n$ such that any "left-rotation" of its words constitutes a correct and meaningful phrase. The left-rotations of $S$ are: \$...