Questions tagged [no-computers]

A puzzle designed to be solved without using calculators, online decoders or computer programming. You're still allowed to use a computer to post the solution; Stack Exchange doesn't support smoke signals yet.

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276 views

Around The World

It's White to move and checkmate Black in 36 moves. Have fun! Oleg Pervakov and Karen Sumbatian, Shakmaty v SSSR 1990 P.S.-To me, it’s crazy that the title hasn’t been taken yet! Hint:
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3answers
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Cipher text on an ancient wall

The following text was found written on the wall of an ancient tomb: $\text{DXFDMKEPU}$ Can you decipher what it means? Nearby the wall, this piece of parchment was found. Perhaps it is a clue ...
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1answer
125 views

Footmen And Friends #2: Leapfrog

Seeing as the pilot episode was a major success, with an outstanding and correct response from one of our viewers, it’s time for Episode 2. Remember, we show puzzles with kings and pawns only! Those ...
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3answers
800 views

Longest word with no adjacent or repeated letters

Idea from Longest word with adjacent letters on a keyboard and Longest word with adjacent letters on a keyboard (without using any letters twice) What is the longest word found in the Merriam-...
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2answers
189 views

What Goes Round (Begriddled logic puzzle)

Join adjacent numbers in the below grid to reveal the hidden content. The rules are: 1: Join all pairs of vertically and horizontally adjacent numbers that are the same. 2: Join all pairs of ...
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2answers
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Another simple jugfill problem

You have two 4 liter jugs and one 5 liter jug. All of them are empty. You can fill up a jug to its full capacity, empty it or pour one jug into another one until the jug you pour into is full or the ...
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3answers
6k views

First digit of 3^2020

Inspired by The last digit for 3^(2019) Can you find the first digit of $3^{2020}$ without a computer?
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1answer
336 views

The Rambling Monster

The Rambling Rook is back, but this time, they are a true monster! It’s White to move and reach a winning position in 101 moves. Gijs van Breukelen, Schakend Nederland, 1981, Special Honoring ...
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2answers
993 views

First digit of 2020!

This is a follow up to First digit of 3^2020 Can you find the first digit of 2020! (factorial) without a computer?
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1answer
408 views

A unique word: Says Grandpa

"Very interesting word", said Grandpa. "Could be the only word with this property" "What property?", I asked "At least 9 letters long and first four letters are same as the last four letters! ...
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7answers
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I would like to buy 11 liters of milk please

This is somehow follow up question to How to measure 5 litres using 10L, 7L and 3L vessels You went to a farm to get some milk. You only need $11$ liters of milk and ask for it to the farmer, but our ...
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2answers
169 views

Another milk jug question

Recently there was a jug pouring competition, and I got to thinking if this was the question with the most number of moves. It turned out that it was. If you have three different sized jugs all less ...
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1answer
154 views

Numbers with vowels used twice

This question is linked to Numbers in series If you write out the numbers the British way (using "and") What is the smallest number that has all the vowels used exactly twice. What is the ...
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2answers
368 views

An Antichess Puzzle

There's a fairly popular alternate version of chess called Antichess, or Losing Chess, or about seventeen other names. In this variation, the pieces move as usual, but the rules are slightly altered. ...
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332 views

Where art thou, oh native rooks?

Here’s a tough puzzle for you all today! Given that both White and Black conspired to reach this position as briskly as possible, where standth White’s native rooks (the one from the starting ...
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1answer
186 views

Humans, vampires and mirrors part 2: the triangular mirrors

Find part 1 (without triangular mirrors) here. Here is a room composed of $10 \times 10$ squared cells. Each cell can be empty (𝑋) or contain one of the following: a double-faced mirror ( / or \ ); ...
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1answer
485 views

Recipe for diced shark fin

How may the following shark-fin-shaped Goal distribution be cooked up with 44 ingredients in a roll recipe R based on the roll sum of two 6-sided dice with non-standard allotments of dots? Goal: ...
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1answer
424 views

Humans, vampires and mirrors

Here is a room composed of $10 \times 10$ squared cells. Some cells contain a double-faced mirror ( / or \ ) that reflects the light with an angle of $90°$ on both sides. The other cells can be empty (...
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2answers
403 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 ...
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1answer
172 views

What is the minimum-value piece combination necessary to checkmate in this game of Crazyhouse?

Imagine you're playing a game of crazyhouse, which operates like standard chess, except that you have a pocket of captured pieces that you can drop on the board in any legal location as your move. ...
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1answer
1k views

The hardest crossword you'll do today!

This could well be the most difficult crossword you do today! Please note that the use of Google and other search engines is STRICTLY FORBIDDEN. (Of course, I have no way of policing this, but if ...
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6answers
611 views

A looped building with Prime rooms lighted

Imagine a building with 200 consecutive connected rooms as shown below. The shape is not important. It could be a circular loop building. You do not know the room numbers but you are told that they ...
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1answer
174 views

Found this on The Ohio State University campus on a pillar relatively hidden from view. Any leads? I’m clueless

Here is the photo of the code... I think. I don’t know what it could be, but it was duct taped to a pillar for several weeks before I was kicked off campus from COVID-19:
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841 views

Color Logic - Find the rule

Find the rule specified in the image below. (Where I got it)
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1answer
3k views

MASTERING Sudoku

Fill the grid with letters M, A, S, T, E, R, I, N and G. Standard Sudoku rules apply. Additionally, the words on the right-hand side must appear in the given orientation (across/down). Each word ...
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1answer
106 views

Footmen And Friends #3: Eviction

Welcome to Episode 3, where we have a strange puzzle for today. Pawns aren't legally allowed on the first and eighth ranks, but today we make an exception for the sake of creating another long but fun ...
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4answers
3k views

A six letter body part

The question relates to a recent puzzle: One is outstanding, another doesn't belong : Says Grandpa Take the word PARENT for example. If you take 2 consecutive letters out, the remaining four ...
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1answer
885 views

And another one bites the dust

I recently found an extraordinary moremover online today. Have fun finding the solution! It’s White to move and mate in 19 moves! Bonus: Explain the title in relation to the solution! Jozef Lozek, ...
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1answer
174 views

Footmen And Friends #1: A Long Ways Away

Tonight premiers the first show of Footmen And Friends, a show dedicated exclusively to kings and pawns. Let's give these soul-men of chess a chance to shine instead of their big sisters and brothers! ...
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2answers
444 views

To Win The Right To ****************

I found this nice little problem on Tim Krabbe's website the other day. I found it so unique and beautiful, that I felt compelled to share it here as a puzzle to be solved. Please do not use a ...
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1answer
290 views

A new year's mathematical mystery

Sam, Magnus, and Olivia each try to write the number 2020 as the sum of consecutive positive integers. They each use more than one integer, a different number of integers to the others, and none of ...
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3answers
284 views

A Multitude Of Mates In 5-An Original Chess Puzzle

Here’s a toughie for you-and no computers allowed! I have created this unique chess puzzle which white mates black in many different ways, all in 5 moves, no matter what black does. Options do exist ...
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1answer
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Four mathematicians and their ages

Four mathematicians, none yet a centenarian, meet for coffee. The graph-theorist among them noticed that the common divisor graph of their ages (that is, the graph whose vertices are their ages, two ...
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5answers
2k views

Nice no-computers way to find limerick primes?

A limerick number is a 5-digit number whose digits are in the form of a limerick rhyme scheme: $aabba$. How many limerick primes (limerick numbers which are also prime) are there? The answer is ...
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4answers
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Paint 21 Squares of a 7×7 Board Without Forming a Rectangle

Got a nice puzzle from my friend, when he was competing in IWYMIC/IMC 2011. Paint $21$ of the $49$ squares of a $7 \times 7$ board so that no four painted squares form the four corners of a rectangle....
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1answer
158 views

Against the Grain, Salt to the Sea: Sudoku

Against the Grain, Grain of Salt, Salt to the Sea, Sea...badge? What Badge? Of course, guessing is not fun, right? Anyway, congratulations to anyone who get this! :D
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1answer
190 views

Just Another Sudoku for PSE

Crafted with love for PSE, <3
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4answers
1k views

Series of interestingly increasing words!

What is the next word(more than one is possible!) in the below sequence of words: NO, ATE, OPTS, _ _ _ _ _ ? Note: 1 Only standard English words(as per Oxford English Dictionary) are to be ...
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5answers
425 views

Multiple XOR operations

Find $8$ distinct $8$-bit numbers, each with $4$ bits set to one, such that the cumulative XOR of these bytes is $10101010$. I imagine there are multiple answers, so the first correct answer wins the ...
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1answer
312 views

Geographic alphametic riddle with European flags

Every letter stands for a digit in base-10 representation, different letters stand for different digits, and leading digits are always non-zero. $\quad$ PLUS $\quad$ $\quad$ IS EQUAL TO $\quad$ ...
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1answer
221 views

A Remote Location

Here be a simple problem For the keen directmate eye White to move and win In seven moves, Black shall die However, I remember now a relative Long ago did he begin to live About a two decades or ...
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2answers
399 views

A series of fortunate transpositions

Using only a sequence of transpositions, see if you can take this: to this: while maintaining English words on each of the three horizontals. At each step, you may transpose any two neighboring ...
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1answer
141 views

Another series of fortunate (and sideways) transpositions

Using only a sequence of transpositions, see if you can take this: to this: while maintaining English words on each of the three horizontals. At each step, you may transpose any two neighboring ...
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3answers
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 ...
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2answers
503 views

Pensive Nonogram - Two-Colour Puzzle

Fourth two-colour puzzle in the 32nd issue of Mega Pixel Puzzles by Puzzler.. I’ve made some progress, but I am stuck. Can you help me find my next move in it? (The puzzle is below)
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Make a hexiamond star by hand

Using some or all of the hexiamonds (pictured), make a star. You may flip pieces. The usual tiling rules apply, no overlaps, no gaps. Use only one or none of each piece. Answer is unique. Target shape ...
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1answer
209 views

Put the numbers $1, 2, …,16$ in circles

Put the numbers $1, 2, 3, ..., 16$ in circles so that the sum of the four numbers on each side of the triangle should be equal.
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268 views

A Logician's Game of UNO Flip

Two players are in the middle of an ongoing one-on-one game of UNO Flip, with all its standard rules in effect. Play is currently Light Side Up. It is Player B's turn. Player A has 3 cards remaining, ...
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1answer
127 views

A Breeze Through

Here's a small problem for you all to breeze through tonight! It's White to move and selfmate themselves in 7 turns. Can you tell me what the special concept is that arises from this problem? As ...
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1answer
177 views

Down The Board-Selfmate In 10 Moves

Here's a miniature selfmate puzzle that I composed today. I just got an idea and I managed to successfully create it. I got the basic idea down to just 9 pieces, none of which are promoted. It's ...

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