Questions tagged [no-computers]

A puzzle designed to be solved without using calculators, online decoders, or computer programming. Using a computer to type and post the answer is allowed; the spirit of this tag is to make people solve the puzzle on their own.

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11
votes
2answers
566 views

When was Ensquare born?

Professor Matlogic posed this question to his smartest math student: "Famous mathematician Ensquare was born on this day, this month and this year AD at this time (hour and minutes) pm. True to ...
6
votes
1answer
731 views

Three cups and a ball

I am walking down the streets of Paris when a street performer approaches me. He has a row of 3 cups facing down on a table. He places a ball under the left cup. He proceeds to swap pairs of cups, ...
5
votes
1answer
133 views

Wormeus And The Multiple Stickotaurs

Here is the fifth maze in the Wormeus series. This time Wormeus is faced with multiple Stickotaurs and multiple Universes. Different universes are connected via … wait for it … drum roll ...
6
votes
7answers
4k views

Find the longest string of words such that the (4 letter) end of one word is the start of the next [closed]

Here is an open-ended challenge. Find the longest series of English words such that the final four letters of word $n$ are the same as the first four letters of word $n+1$. Example (3 words) ...
8
votes
3answers
2k views

Changing WATER to STEAM

How do you change the word Water to the word Steam by changing one letter at a time? The newly formed words must be from Merriam Webster dictionary. No proper nouns, abbreviations or acronyms. No ...
7
votes
1answer
272 views

AnaCross II: it's bigger now

So, I've prepared another AnaCross puzzle. The rules are exactly the same: At the end of each row is a pool of letters; those letters are the letters that go in that row of the crossword. Normal ...
5
votes
1answer
196 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,...
4
votes
2answers
184 views

Cyclic squaring

Find a complex number $a$, which satisfies the following conditions: If you square $a$, you get a different complex number $b$. If you square $b$, you get a complex number $c$, which is different ...
7
votes
4answers
963 views

A Five City Loop, starting and ending in MA

Complete a loop of five large cities. The starting city name starts with the letters MA. Each of the following cities starts with the last two letters of the previous city name. (Like PARIS ISTANBUL ...
2
votes
2answers
310 views

Four Mathematicians, Four Poker Hands and Four Clues

These four mathematician friends play poker every Saturday night. They always have a twist for the very last hand, just for fun. This Saturday the twist was “Factorial Clues”. The rule for the last ...
6
votes
1answer
561 views

Flat share share

This is a sequel to Gentrification in Chessshire. Due to the febrile state of the Chesster housing market you and your flat mates are forced to rent out half your place to another group of sharers. ...
8
votes
1answer
766 views

Inequality derived from a famous problem

Let's have the following inequality: $\frac{2}{3}(\sqrt 5-1)^3\lessgtr\sqrt[3]{2}$. Which part is greater, the left or the right? No calculator solutions are accepted.
10
votes
1answer
418 views

A Cryptic Cryptarithm

An entry in Fortnightly Topic Challenge #48: Unusual tag mix Solve these puzzles to reveal why I made them. Matriarch mostly prepared oats for American airline location? (8) AIRLINE + LOCATION = ? 51 ...
11
votes
2answers
510 views

Mosaic by Albrecht Dürer

This is a visual puzzle (known as "mosaic" or "fill-a-pix") with the same rules as MineSweeper: The grid is to be filled with colored and white tessera. Choose whatever color you like for the colored ...
3
votes
1answer
195 views

Quadruped Mosaic

This is a visual puzzle (known as "mosaic" or "fill-a-pix") with the same rules as MineSweeper: This puzzle has exactly 100 x 100 cells. The grid is to be filled with colored and ...
16
votes
1answer
769 views

What number goes in the ?? box?

A simple pattern puzzle What is the number in the ?? box? Why? No programming please.
5
votes
2answers
233 views

Wraps and Loops—Some Concrete Examples

This puzzle serves as the more concrete sequel to my previous post; in particular, see that post for the rules of the game. Rather than (implicitly) demanding a description of a polynomial-time ...
-1
votes
1answer
88 views

Consecutive number division puzzle 2 [closed]

Find 4 consecutive numbers that divide 𝑤, 𝑥, 𝑦, 𝑧 respectively, where 𝑤, 𝑥, 𝑦, and 𝑧 are also 4 consecutive positive numbers greater than 1, or prove it's impossible. Bonus: What if w > the ...
7
votes
5answers
638 views

What a coincidence or eighteen is not seventeen take two

Since I botched my first attempt at posing this puzzle, let me try again, this time hopefully closing all loopholes by dropping the packing angle and making this a purely geometric puzzle: The figure ...
5
votes
1answer
228 views

Kill me or I kill you first!

How many mates are possible under 10 moves? Rule: Mate can go both ways. Under 10 moves. Feel free to let White or Black move first. Board diagram: Apronus PGN Viewer board for white taking the ...
10
votes
2answers
596 views

Missing checkmates in one

Have you ever missed a one-move checkmate and immediately realized it after making your move? If you have, you just might have what it takes to crack this problem. Let's take an example: g4 e5 ...
6
votes
2answers
2k views

Eighteen is not seventeen

This question is not the same as Adding coins inside a ring of coins From a pile of equal size perfectly round coins take eighteen and make a perfect ring. Show that you can fit at least sixteen more ...
12
votes
1answer
195 views

Wormeus and the Stickotaur (maze 3)

This is the third maze in the Wormeus series. Previous puzzles are here and here This shouldn’t be too difficult but contains a cute gimmick that isn’t possible in the original Theseus mazes sans the ...
8
votes
5answers
1k views

Split 1 through 6 into a product of 24 and sum of 12

How many ways are there to split the numbers 1, 2, 3, 4, 5, and 6 into two groups, such that the product of the numbers in one group is 24 and the sum of the numbers in the other group is 12? An ...
30
votes
7answers
6k views

Another Easy Mate in 1

Standard chess rules apply, the board is not rotated (i.e. white pawns move upwards), no lateral thinking is needed. Simply find the one move for white which mates the black king. This puzzle was ...
3
votes
1answer
73 views

Divisors ending with digits 0-9 each

What is the smallest positive integer, which has - for each of the digit 0-9 - a divisor ending with this digit?
7
votes
1answer
216 views

A 3x3 grid with common factors

A $3 \times 3$ grid $G$ is filled with every number from the set $\{2,3,5,6,7,11,14,15,30\}$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that ...
11
votes
4answers
947 views

Deriving a 3x3 grid from another one

A $3 \times 3$ grid $G$ is filled with every number from $1$ to $9$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that are greater than $G_{ij}$....
0
votes
1answer
85 views

Self-indulgent numbers

Let's call a positive integer N self-indulgent of degree K>2 if for every positive integer k<K the following is true: More than half of the first k multiples N,2N,...,kN of N contain with ...
8
votes
1answer
337 views

Manual tiling with 8 dodecadudes

Here are 8 dodecadudes. (Drawn from the very numerous dodecadrafters, made from 12 half equilateral triangles, dodecadudes are a subset of 770 pieces with sharp points and narrow necks excluded). ...
9
votes
1answer
167 views

Wormeus and the Stickotaur (maze 2)

Here is another Wormeus maze, following a previous puzzle that is yet to go viral. Wormeus has to eat all the apples without dying a horrible squishy death at the hands of the Pink Lady Stickotaur. I ...
4
votes
1answer
742 views

Beating at Eating, a logic-grid puzzle for literal logicians

Name Surname Dessert 1 Agatha Greed cream puffs 2 Bugsy Forager trifle 3 Delilah Eatalot cheesecake 4 Chuck Hunk ice cream Four friends held a competition to see who could eat the greatest amount ...
11
votes
3answers
1k views

Swapping 3 knights in a 4x4 grid

Can you swap black and white knights in this 4x4 grid? There is one important constraint: at no point can a knight be under attack by an opponent knight. Knights move using standard chess moves (L ...
11
votes
2answers
356 views

Wormeus and the Pink Lady Stickotaur

Wormeus lives in a labyrinth containing lots of apples. His main ambition in life is to eat as many apples as possible but his nemesis, the evil Pink Lady Stickotaur, has other ideas – if you pardon ...
19
votes
1answer
618 views

Quartum non datur

Can you give a good rational approximation of $$\sqrt[3]2 \times \sqrt[4]2$$ without doing any significant maths? Hint: Attribution: Mine.
9
votes
2answers
816 views

Don't bully your little sister at chess

This puzzle was inspired by @RewanDemontay's puzzle De-zephyr The Solution!. Rewan kindly granted me permission for making this puzzle and citing his as my source of inspiration. I thought of naming ...
2
votes
0answers
197 views

This ᴀɴᴅ That musical act from the past [closed]

Below is a fill-in-the-blanks three-part list of variously-venerable musical acts of the form “________ ᴀɴᴅ ʜɪs/ᴏᴜʀ/ᴛʜᴇ _________.” The example of “Paul Revere ᴀɴᴅ ᴛʜᴇ Raiders” has been filled in for ...
14
votes
1answer
570 views

Candy Button Paper

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Title based on this xkcd. Your biggest dream has come true: you have an infinite supply of your favorite five-flavor candy button ...
12
votes
1answer
417 views

AnaCross: A crossword made of anagrams

This is a new type of puzzle I've devised: the AnaCross. Nothing new under the sun and all, I'm sure someone has made one before, but I've never seen it. The rules are pretty simple. At the end of ...
1
vote
1answer
190 views

Probability of a successful DT Cannon

In multiplayer Tetris, there are a number of opening setups that let you send powerful attacks very quickly. One popular opening is the DT Cannon, which allows the player to very quickly send a T-Spin ...
12
votes
1answer
208 views

Three white queens, two white knights, and one rook on a chess board

On an 8 x 8 chessboard, place three white queens, two white knights, and one white rook so that every cell of the board is under attack by at least one piece not standing on it. Source: https://www....
3
votes
1answer
157 views

Non-increasing arrangement

We are arranging the numbers from 1 to 8 in an order so that three consecutive terms cannot be increasing. For example, 12345678 isn’t allowed but 81436572 is. How many ways are there to do it? Please ...
19
votes
1answer
451 views

Escape from Sudoku!

An entry in Fortnightly Topic Challenge #50: Escape Rooms I hesitated to enter this in the Escape Room FTC, but I definitely was inspired by the challenge to create this puzzle, and it is, in some ...
4
votes
1answer
1k views

Find three ways of forming the number 100 using 3,3,5,7

As it says in the title. Rules: anything not explicitly allowed is forbidden. use 3, 3, 5, 7 and multiplication, division, sum, difference, unary minus, and exponentiation in any order. Parentheses ...
4
votes
1answer
151 views

Chess - I will eat!

Suppose that you are playing White, and your aim is to eat a black piece (pawns qualitfy) in the fewest moves as possible and Black are not cooperating at all, and, even more, Black's aim is to ...
13
votes
1answer
2k views

A Math Riddle: But the math does not add up

Grandpa had a lot of different books of stamps on his desk. He was counting them. I was curious. “What are all those stamps Grandpa?” “I just got back from the Post Office son and bought a bunch of ...
9
votes
1answer
400 views

Trivia… sudoku

An entry in Fortnightly Topic Challenge #49: Pub Quiz Camouflage Please do not search the answers online (hence the no-computers tag), otherwise it would be too simple to solve this puzzle. I tried ...
5
votes
4answers
6k views

Special 5x5 Sudoku-like table

This is a special 5x5 Sudoku-like table. Each row, column, and diagonal contains digits from 1 to 5 (including diagonals obtained by wrapping around the edges). To filter duplicates (by rotation, ...
30
votes
5answers
5k views

How can 3 queens control the white squares?

It is well known that there is no way of arranging 4 queens on a checker board in such a way that every square is occupied or threatened. Now consider a slight variation where we only need to cover ...
6
votes
2answers
337 views

Twin primes and divisibility

Let $p$ and $q$ be a pair of twin primes. Find the smallest possible value of $a+b$ where $a$ and $b$ are positive integers such that $p\;|\;(a+qb)$ and $q\;|\;(a+pb)$. This puzzle is my own ...

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