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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42
votes
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 ...
10
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6answers
613 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 ...
1
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1answer
175 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:
18
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2answers
852 views

Color Logic - Find the rule

Find the rule specified in the image below. (Where I got it)
33
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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 ...
2
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1answer
109 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 ...
23
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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 ...
6
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1answer
886 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, ...
5
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1answer
176 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! ...
4
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2answers
447 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 ...
9
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1answer
292 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 ...
5
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3answers
291 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 ...
20
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1answer
1k views

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 ...
11
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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 ...
5
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1answer
161 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
6
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1answer
280 views

Just Another Sudoku for PSE

Crafted with love for PSE, <3
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 ...
1
vote
5answers
440 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 ...
10
votes
1answer
315 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 $\quad$ ...
5
votes
1answer
223 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 ...
14
votes
2answers
402 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 ...
4
votes
1answer
145 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 ...
14
votes
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 ...
7
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2answers
526 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)
14
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2answers
1k views

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 ...
4
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1answer
215 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.
0
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0answers
295 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, ...
3
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1answer
130 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 ...
7
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3answers
700 views

Tricky Tricky!-Can you find the secret?

Here's a selfmate problem that just might be baffle you! Thus, I name it "Tricky Tricky!" It's White to move and selfmate themselves in 8 moves. Can you find the secret? As always, no computers ...
5
votes
1answer
119 views

Sum of All the Others

There are ten different 10-digit decimal fractions, one of them being equal to the sum of the other nine. If each number has 10 unique digits, not counting the 0 before the decimal point (for example ...
18
votes
2answers
968 views

Anagram fills all the blanks

Continuing with the theme " Same word fills all the blanks" here is a riddle where the anagrams of ONE WORD fill all the blanks. One concession: Apostrophe allowed. NO using Anagram Solver or any ...
0
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1answer
125 views

Confusing letter

I once received a letter where all letters of the alphabet was shuffled around. The task was then to find out what each letter was and then read the letter. I wrote a little letter for you: Be ...
-3
votes
1answer
410 views

123456789 = 100 with three operations? [duplicate]

Given the sequence 123456789 You can insert three operations (+,-,X,/) into this sequence to make the equation = 100. Is there a way to solve this without brute force?
7
votes
1answer
242 views

Excited Raichu vs the Dream (Chess Puzzle)

(Source: An actual tournament game I played all the way back in 2016) I had the weirdest dream last night… It started out normal enough, which for me, is basically nothing… but then I woke up, ...
16
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3answers
3k views

Prime to Prime: Get all first 25 Prime Numbers using up to 4 Primes

The first 25 Prime Numbers are 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97 Using up to 4 prime numbers and the following mathematical operations, get all the 25 primes. + ...
7
votes
1answer
299 views

The Newest Cycle

A wonderful new chess problem has appeared lately that is most wonderful. I am here to share it with the world today. But you must solve it in order know about it’s glory! It’s White to move and ...
9
votes
1answer
491 views

Twelve Labours - #12 Pluto Pups

This puzzle is part of the ‘Twelve Labours’ series, but can be solved independently. Previous instalments can be found here: Prologue | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 It was ...
12
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2answers
800 views

Hearts and Spades in a Row

From a deck of playing cards remove hearts ace to seven, and spades ace to seven. Now place them on a table in a row so that the number of cards between the two aces is 1, the number of cards ...
3
votes
1answer
231 views

Rotary phone with numbers and letters

I am going to organise a quest for teenagers. I have a vintage phone like below: I am looking for ideas how to use the rotary phone with numbers 1,2, ..., 9, 0 and letters A, B, C, F, H, I, K, L, M, ...
8
votes
1answer
707 views

(Im)Possible 8-Puzzle

Can you solve this 8-puzzle in 16 moves or less?
3
votes
2answers
338 views

What was Grandpa really doing?

"Guess what happened during my walk". Said Grandpa "I saw gods in a ghetto"! He continued with a smile. "What?" I said. "Well, not really. But can you guess what I did?", Grandpa asked. ...
4
votes
1answer
112 views

You Tell Me What To Choose

I found this nice problem in A.C. White’s 1912 book “The Theory Of Pawn Promotion” the other day. Enjoy! It’s White to move and checkmate Black in 5 moves, Don’t forget to explain the title! ...
9
votes
3answers
466 views

So, what's to do?

It's White to move and draw the game. What must White do? You must provide proof for your claim of what's to be done by any reasonable means. No looking up the solution please! Nikita M. Plaksinm ...
1
vote
1answer
195 views

Especially Special

Here's a special and interesting chess problem that I came across the other day. As usual, no using a computer and no Googling or anything like that for the solution. You must use your own brain ...
2
votes
1answer
216 views

The Sea Snake's Slithering Problem

Here's a really long chess puzzle, not made by me, that has the "sea snake" theme, which just basically means that it's super long. It's White to move and checkmate Black in 122 moves. Миљанић, ...
3
votes
2answers
192 views

Back in time, in my time, all the time

I present to you all a highly interesting problem that I came across awhile ago on Tim Krabbe’s site. It’s White move and win, i.e. reach a winning positon, in 21 moves. David Gurgenidze & ...
2
votes
4answers
635 views

Grid Puzzle - Paint

A student was found making Graffiti in the teacher's office. He was punished and was asked to repaint the wall of the room. The teacher gave him a grid to show which part of the wall should be painted ...
10
votes
4answers
2k views

What's the most rewarding path?

Get from the top-left to the bottom-right using only right and down moves. Pick up as much gold as possible. There is only one maximum.
11
votes
3answers
1k views

A String-based Puzzle: Can you get from the string “baa” to “bacaccacacccc”?

Goal: Go from the initial string to the final string by applying a sequence of string replacement rules. You are given the following: Initial String - baa Final String - bacaccacacccc You ...
3
votes
2answers
234 views

Minesweeper puzzle - Too many twos

A Gobo is caught for leaving the school for the lnternet bar to play computer games without permission. He is asked to solve a problem. Put 4 mines in a 3 by 5 minesweeper grid to fill ALL the other ...

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