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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3 votes
1 answer
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Justifying a redouble

This puzzle is derived from a real game of bridge I played on Bridge Base Online. I was sitting North on board 9 (N dealer, E-W vulnerable) and the bidding turned out like this: West North East South ...
Parcly Taxel's user avatar
  • 6,954
0 votes
1 answer
137 views

Techno-Culinary Brain Teaser: Unravel the Code in the Kitchen

The answer is one word. The rebus:
web adventurer's user avatar
1 vote
0 answers
115 views

Find the ciphering method 4

Link to the entire series. The message: ...
web adventurer's user avatar
4 votes
1 answer
326 views

Find the ciphering method 2

Link to the entire series. The message: 3, 53, 48751, 9247757, 294914580539 The answer is a 13 letter word: UNDERSTANDING Hint 1:
web adventurer's user avatar
2 votes
1 answer
255 views

Find the ciphering method using deciphered message

Link to the entire series. Ciphered message: ...
web adventurer's user avatar
0 votes
0 answers
73 views

Find the largest number with unique digits, that is divisible by each of its digits [duplicate]

Find the largest number with unique digits, that is divisible by each of its digits. For example 132 has unique digits and is divisible by 1, 2 and 3. But it is not the largest such number. Can you ...
Teodor Dyakov's user avatar
31 votes
13 answers
6k views

2 vs. 1.005^200

Without using a calculator or a computer can you determine which of these two numbers is bigger: $2$ or $1.005^{200}$ ? I saw this puzzle in a YouTube video, which I will post later.
Dmitry Kamenetsky's user avatar
-2 votes
1 answer
114 views

Fill a 4x4 grid with minimal sum of positive integers in a way that adjacent cells contain numbers of different parity

Find a 4x4 grid containing 16 unique positive integers with minimum sum, such that adjacent numbers have different parity.
web adventurer's user avatar
6 votes
1 answer
292 views

The Nine Gardens Of Eden

This puzzle is part of the Monthly Topic Challenge #11: Now in 3D. There are nine distinct known three-cell Garden of Eden patterns in the Life Without Death cellular automata, including the two well-...
Scratch---Cat's user avatar
1 vote
1 answer
255 views

A take on custom ciphers

There is something hidden in the text below. Can you find out what it is? Note: no computers or tedious work required. ...
DL33's user avatar
  • 701
12 votes
3 answers
4k views

I Hate Traffic And So Do You

I need to travel through the city from my house to school, but the traffic is horrible right now. I can only move along the city's grid with the following conditions: • blocks with traffic (marked in ...
RonnieChen's user avatar
2 votes
1 answer
247 views

The minimalist game master [closed]

A game master tells his party of players that he has converted to the school of minimalism, and is going to do away with all of his dice in the campaigns they play from now on. In the place of dice, a ...
Feryll's user avatar
  • 2,172
0 votes
0 answers
149 views

Puzzle "railway game set"

Alisa completes a railway game set which allows us to make various closed railway routes with crossroads. It is need to put the “rails” parts in the kit, as well as four types of “crossroads”: corner (...
Nick's user avatar
  • 1,699
-3 votes
1 answer
189 views

Giraffe Necked Island

Where is this island, and why is the title of this question "Giraffe Necked Island?"
Ronchen Luo's user avatar
4 votes
1 answer
294 views

A different Crack the Code puzzle

This is a different Crack the Code and get the word puzzle. Here, instead of letters, actual words are hidden. The final word is a 7 letter famous person. That word consists of several words. I only ...
RogerA's user avatar
  • 4,641
3 votes
1 answer
351 views

Micropoker: small hands on deck

Raise your hand if you are ready for micropoker, which minimalistically resembles 5-card poker. The deck has just 8 cards with 2 suits of 4 cards each. A hand is dealt as 3 cards that are final, with ...
humn's user avatar
  • 21.8k
20 votes
7 answers
1k views

Save now! All the digits at half the price

... or double the price depending on where you're coming from Consider the set $PD10$ of pan-digital ten-digit numbers, i.e. positive whole numbers whose decimal representation has each of the digits ...
loopy walt's user avatar
  • 18.2k
8 votes
1 answer
1k views

Important Alien Message

A strange alien transcript, alongside what is believed to be a partial key, was recovered the other day. Scientists aren't sure what the message might contain, but theories point to some sort of ...
ExecutionByFork's user avatar
13 votes
1 answer
711 views

Find the lower 8-digits number such that

This one come from newspapers in France, where this week is the "mathematics week", and some problems are proposed to kids. This single one is easy and funny: Find the lowest 8-digit number, ...
franck vivien's user avatar
10 votes
1 answer
292 views

Equilibrium of differences

There is a subtraction equation written on the board, with three digits minus three digits, and the first digits both fixed. Alice and Bob need to fill in the remaining 4 digits (A~D below) using 4 ...
Pumbaa's user avatar
  • 802
10 votes
1 answer
745 views

Numbers whose product of digits is a multiple of sum of digits

Find three consecutive numbers, greater than 10 and none with a digit 0 in it, each of which is such that the product of its digits is a multiple of the sum of its digits. What about four or more such ...
Bernardo Recamán Santos's user avatar
3 votes
1 answer
347 views

How to find the value that makes this addition equation work without using a computer?

The following image represents the addition of 2 five-digit numbers, where 10 different letters represent 10 different numbers (0~9). What does PUZZLE equal? (There are two possibilities and a ...
Pumbaa's user avatar
  • 802
12 votes
1 answer
689 views

Friends and Enemies

Here is a short puzzle I made: There are 10 people arranged in a row, and each of them has a friend and an enemy also present in the row. Your goal is to identify the friend and enemy of each person. ...
VeryStaleAndDeadAccount's user avatar
15 votes
1 answer
526 views

What does the fox say?

I found a piece of paper on the hallway floor of my friends apartment complex, and on it is an oddly written question and an unreadable response. Can you figure this out? Question: WHAT DOES THE FOX ...
Hawkeye's user avatar
  • 2,438
15 votes
1 answer
1k views

Trust me: you do not want to go down this road with me

Every cell has a digit from 0 to 9 or one of the four operation symbols +, −, ×, and /, signifying addition, subtraction, multiplication, and division respectively. No digit appears more than once in ...
msh210's user avatar
  • 11.7k
3 votes
1 answer
247 views

Two many restrictions

Using only the number 2 several times, form the numbers 2, 22 and 222. The following operations are available: addition subtraction multiplication division exponentiation Each of these operations ...
Manish Kundu's user avatar
  • 2,584
5 votes
1 answer
319 views

What is a Nature Word™?

This puzzle is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Nature Word™. ...
mathlander's user avatar
-5 votes
1 answer
284 views

What season was it?

A puzzle maker wrote this in his notebook as a holiday puzzle: Th bbie sartd unning. What season was it?
mathlander's user avatar
-5 votes
3 answers
510 views

125034 v1.0.0 / WR 1713-11-07

I am developing an app that generates puzzle games every day (https://125034.pages.dev/). Their basic form may be viewed as Wordle in math, Sudoku in 6 grids, or Einstein's Riddle in 1 row. If today ...
a life's user avatar
  • 13
28 votes
2 answers
2k views

A logician's Bingo

Mark some cells on the following Bingo board, so that all statements in marked cells are true AND all statements in unmarked cells are false. A Bingo here is a set of five marked cells in a row, ...
Bubbler's user avatar
  • 11.5k
5 votes
3 answers
416 views

Laziest Checkmate

Consider a game of chess where White delivers checkmate in their $X^{th}$ move. For all the pieces that remain on the board at the end of the game, consider their Manhattan Distances from their ...
Manish Kundu's user avatar
  • 2,584
4 votes
1 answer
175 views

Packing the Primes

Here is a 5x4 rectangular wordsearch (area 20) containing the primes between 1 and 100, {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} (numbers in any ...
Amoz's user avatar
  • 23.1k
10 votes
3 answers
2k views

The Universe's Secret

To find the universe's secret, first solve the Sudoku variant with #s 1-7 only. No number may be repeated on any diagonal. No numbers go in the squares with red or green dots. Then use the solution ...
JLee's user avatar
  • 17.5k
5 votes
6 answers
412 views

How many digits does $7^{100}$ have?

I'd like to estimate $7^{100}$ without using these new-fangled computers everyone is talking about, but I think I need your help. Please estimate $7^{100}$ without the use of a computer. My friend ...
Michael Engen's user avatar
14 votes
15 answers
8k views

The computer can't do anything I couldn't do with pen and paper

If you want to know how much $3^{100}$ is, you can just type it into a computer and it will spit out a really big number. But that is no fun. The task is to estimate $3^{100}$ with some computation ...
quarague's user avatar
  • 1,309
10 votes
2 answers
1k views

A square number that is a concatenation of at least 25 squares

A pen and paper challenge: Write down a number whose square (repetition allowed) is the concatenation of at least 25 nonzero squares. examples 7, 13, 12: Their squares are the concatenation of 2 ...
Retudin's user avatar
  • 7,609
1 vote
1 answer
172 views

Determine the hidden digits in this long division puzzle

The following problem was given in the Eureka journal (October 1963/University of Cambridge). This problem can be solved by hand without computers. There is a unique solution. Have fun solving! Fill ...
Will Octagon Gibson's user avatar
25 votes
2 answers
2k views

What is my favorite brand of pen?

This is an entry to the Monthly Topic Challenge #3: Pencil and Paper Games Given the following valid "tic-tac-toe" boards: What is my favorite brand of pen? Other possible tags to check ...
Amoz's user avatar
  • 23.1k
5 votes
2 answers
369 views

a six-by-six KenKen

The rules of KenKen are as follows: You must fill in the numbers 1 through 6, one number per box, in the grid, so each row and each column contains each number exactly once. Each heavily outlined ...
msh210's user avatar
  • 11.7k
4 votes
2 answers
424 views

Dark time in prison

You wake up. It is pitch dark. You don't know where you are. You feel groggy. The last thing you remember is being in a bar, a sexy young woman appeared out of nowhere, walked straight at you, ...
Florian F's user avatar
  • 26.3k
6 votes
2 answers
1k views

What are the hidden digits in this long division puzzle?

The following problem was given in the Eureka journal (April 1978/University of Cambridge). This problem can be solved by hand without computers. There is a unique solution. The phrase, "exact ...
Will Octagon Gibson's user avatar
3 votes
1 answer
204 views

Sequence of numbers - what comes next? [duplicate]

What is the next number in this sequence, and why? 4 2 3 4 6 2 4 8 3 _? Also, since people here find sequence questions to be arbitrary, the following uses the same rule. What number is next? 4 5 6 4 ...
enkorvaks's user avatar
  • 296
3 votes
1 answer
193 views

Tetromino tilings of a 4x5 rectangle with minimal diversity

This is a relatively easy manual tiling puzzle. In fact the tiling is all done for you, you just have to specify how many of each of the 26 given tilings to use. The puzzle is: Using N complete sets ...
theonetruepath's user avatar
6 votes
1 answer
448 views

Find all integers n such that $\sqrt{n-4 \sqrt{n-19}}$ is also an integer

The following puzzle is from the December 2012 issue of the Eureka journal (published by The Cambridge University Mathematical Society). Find all integers n such that $\sqrt{n-4 \sqrt{n-19}}$ is also ...
Will Octagon Gibson's user avatar
13 votes
1 answer
2k views

The Lufthansa Lottery

In order to pass free time while striking for better pay, some Lufthansa workers organise a lottery where each ticket picks three distinct numbers from $1$ to $11$ inclusive the draw picks five ...
Parcly Taxel's user avatar
  • 6,954
17 votes
7 answers
1k views

Efficient Mowing at PSE

Your task: Find the most efficient mowing path around the dark green bushes that mows (passes over) all of the grass (light green). For those who cannot view the image above, there are 9 rows of 16, ...
JLee's user avatar
  • 17.5k
13 votes
4 answers
785 views

How do I create a sliding-blocks puzzle (specifically like the "Rush Hour" ones) which requires an "ah-hah!" moment?

Background My grandma gave me a set of Rush Hour puzzles as a small child, ever since I could be trusted to not eat the pieces. I still enjoy playing these today and would like to try my hand at ...
bobble's user avatar
  • 10.1k
4 votes
1 answer
146 views

Find the 3 Item Amounts

Last week the store's receipt printer removed lines randomly from each item amount. A technician repaired the printer, but now it adds lines randomly to each item amount! The cashier told me that for ...
JLee's user avatar
  • 17.5k
18 votes
3 answers
754 views

Find the Two Item Amounts

I bought 2 items yesterday and the receipt was incorrect, so I asked the cashier about it. She told me that The receipt printer had been acting funny recently. The total is always correct, but some ...
JLee's user avatar
  • 17.5k
6 votes
1 answer
298 views

Riley-Clued Crossword

The no-computers tag is there only to prevent database dictionary searches. Other computer uses are fine. Below is an ascii version of the image above, for those who cannot view images. All words are ...
JLee's user avatar
  • 17.5k

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