# 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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### Making π from 1 2 3 4 5 6 7 8 9

There have been two other questions here and here that are similar to this one, but this changes the rules up a little. Your job is to approximate $\pi$ using the sequence of digits (in order): 1 2 3 ...
10k views

### Growing anagrams - What is the longest possible list forming a sentence?

This is a challenge for word-puzzle lovers. It might be a bit more of a game than a puzzle, but I think it is not limitless in it's answers, so a final answer could be found (eventually). What is the ...
23k views

### The Longest Word Made from Chemical Symbols [closed]

So, as you probably know, each and every element in the Periodic Table has its own unique chemical symbol, which is either one, two, or three letters long. For instance, Oxygen is represented as O and ...
12k views

### 3:3! It's a football score! [closed]

Given to me, by a friend: How would you make 20, using two threes? You may use any basic operation. And others, such as square roots (the symbol), factorials, etc. Any operation is allowed. Just ...
5k views

### How many consecutive positive integers can you make using exactly four instances of the digit '4'?

Starting at 1 (which is 4 - $\sqrt4$ - 4/4), how many consecutive integers can you make using exactly four instances of the digit '4'? Basic rules: Any operator symbol is "free". Any printed '4' ...
14k views

### The most words that can be made by successively adding one letter to the original word?

What is the largest number of words that can be made by just adding one letter to the original word, where each iteration is a meaningful word? E.g. ...
16k views

### Don't settle for a billion [duplicate]

While Artur is willing to settle for a billion, I'd like a much bigger return on my two matchstick investment. Moving only two matchsticks, what is the largest number that can be created from the ...
4k views

### A rhopalic sentence of at-least 5 words, beginning with as long word as possible [closed]

Rhopalic sentences are sentences which have words whose length is one more than the previous word. eg: I do not hunt birds. I do not know where family doctors acquired illegibly perplexing ...
3k views

924 views

### Interaction of the three kinds

There're three kinds of it. Any two of the same kind will give you that same kind. Any two of the different kinds will give you the remaining kind. What is it? I don't know the answer. I'm trying ...
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 ...
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 ...
419 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 ...
769 views

### Forced selfmate in n-moves [closed]

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 ...
4k views

### Shortest sentence with two auto-antonyms [closed]

You have to use two words that are each their own opposite (auto-antonyms, contronyms, contranyms or whatever you want to call it) in the same sentence. This means that each of the two words in used ...
669 views

### The Longest -1 Word

What is the longest -1 word (or the word worth most in Scrabble for words with the same amount of letters(which is just the addition of all the letter values of the original 'word', no constraints)), ...
3k views

### Can you solve those laser puzzles? (puzzles created by the community) [closed]

So, I was bored and I made a small game for this site! In this game the user who solves the previous puzzle gets to create the next one and they will always be more complex. Website link and string ...
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 ...
5k views

### Longest sentence with each letter repeated n times [closed]

Inspiration: This question was inspired by Word sets with no repeating letters Rules: Sentences can be of any length. Every letter used in this sentence, must be used n times. n can be any number. ...
7k views

### Longest sentence where all words are anagrams of each other [closed]

Won, now own. Rules: A “word” is an entry on dictionary.com. A “sentence” is any text that is grammatically correct, has a complete meaning in the English language, starts with a capital letter and ...
3k views

### Longest arithmetic expression where the answer is equal to the number of letters

You can use any mathematical operations represented by English words. These English words must be found in a commonly used dictionary. Spaces are neither letters nor words. You can not use the same ...
856 views

### 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 ...
1k views

### Chess Game of Life

A bishop and a rook, of opposing colors, start on opposite corners on the same side of a chessboard, oriented as in the following picture: They then proceed to play a game of cat-and-mouse. Rules ...
1k views

### Knight on the keyboard

You are given a QWERTY keyboard, and are allowed to choose where you wish to start. You are only able type in the same way a knight is able to move on a chessboard (but in this case, on the keyboard). ...
555 views

### Bouncing Robots: Graphical Puzzle [closed]

Robots are indicated by the arrowhead shapes and the labels "r", "y", "b", "g". The label obviously corresponds to their color. The aim of the puzzle is to pick up the shapes and put them down in the ...
12k views

### Infinitely long loaf of Bread [closed]

You are visiting your old friend Mike at Infinitely's Baking Shop. Just as you arrived, he was taking out a fresh, infinitely long loaf of bread. Both of its ends extend infinitely long in a ...
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 ...
325 views