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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Too early in the morning to have SODA?

Each letter shown represent distinct digit...can vary from zero to nine. $COCA$, $COLA$, $SODA$ are three concatenated numbers. Figure these out from the following relation: $COCA + COLA = SODA$
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633 views

Tiling a rectangle with just the Y pentomino

Inspired by this question series, which was inspired by this question. They give rise to beautiful pictures (at least in the eye of the beholder mathematician) and some nice generalizable solutions. ...
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1answer
541 views

This word with a lot of past tenses

This interesting word is full of past Starts with a past tense verb. Add a letter at the end and you have a different past tense verb. Then add more letters at the end and you get yet ...
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2answers
280 views

Word connection squares!

This puzzle is in the spirit of Word connections, but is a more elaborate version of the same idea. In each puzzle, you have a square of seven words of the following form: ...
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2answers
251 views

Square made up with polyominoes

A 3 x 6 rectangle has 2 holes in it as shown. Can you cut it into 3 polyominoes with different areas so that they can form a square? The pieces can’t be flipped when they form the square and two ...
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3answers
462 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 ...
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1answer
364 views

Mini 8 queens puzzle

On a 5x5 chessboard, place 5 black queens and 3 whites queens so that no queens are attacking those who are of different color. Furthermore, the numbers indicate how many queens are attacking the ...
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1answer
481 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 ...
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1answer
619 views

Narcissistic cube asks who are we?

I am a five digit narcissistic cube who likes to display my root right upfront. I also have hidden it in the back of my four digit cube brother. Who are we?
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1answer
354 views

Like totally amazing interchangeable sister outfits II: The Revenge

The sisters have learned a few lessons from their recent debut. They are now ruthlessly efficient outfit-swapping machines. (You know, sort of like Valley Girl Terminators...) They can now sustain ...
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2answers
547 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 ...
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1answer
298 views

Functional Equation: Squeeze it

Determine whether there exists a function $f:\mathbb{R}\rightarrow\mathbb{R}$ such that $$f\big(x^3+x\big)\le x\le\big(f(x)\big)^3+f(x)$$ for all $x\in\mathbb{R}$. Source: Math Excalibur Volume 22 No....
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1answer
522 views

Connect the wires without setting off the bomb

You just saw a planted time bomb! Just 5 minutes are remaining until it explodes and as you are in currently in a rural area (no bomb disposal squad) and you know how bombs usually work it is up to ...
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2answers
296 views

Happy days alphametic

Every letter a decimal digit, different letters for different digits: HAPPY HAPPY HAPPY + DAYS ---------- AHEAD Which digit does each letter ...
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1answer
370 views

The Lucky Number

Lucky numbers are 4 digit numbers that have the following property: they are equal to the sum of the fourth power of their digits. Therefore, they can be expressed as follows: $$1000a+100b+10c+d = a^4+...
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1answer
313 views

Not the “SEND MORE MONEY” alphametic

There is a story that a poor college student sent a telegram with the words "SEND MORE MONEY" to his parents, asking for more money, and asking to fill in each letter with a different digit in order ...
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3answers
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
213 views

One to Eleven Sum to Twenty Five

From the picture shown below, deduce the missing numbers (one to eleven)... none of them repeating. Four Numbers surrounding the Five diamonds A, B, C, D, E, as well as the five numbers in the outer ...
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2answers
211 views

An almost Shakespearian alphametic

Every letter stands for a digit in base-9 representation, different letters stand for different digits, and leading digits are always non-zero. ...
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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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1answer
283 views

Simple Homeworlds puzzle

On this site, we have numerous chess puzzles. however, we do not seem to have any Homeworlds puzzles, the game of space kings (yes this can be tagged outer space thank you very much.) Hence, here is ...
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1answer
484 views

Find The Common Pattern In These Words

You are a super spy, typing on your QWERTY keyboard, when suddenly you received an urgent call from your boss, Caesar. He had urgently called you, defying all protocols, as he wanted to inform you ...
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2answers
169 views

4x4 grid equations version 2

I decided to make another one of these, because they are fun and this one is rather different. Can you place all numbers from 1 to 16 into cells, such that the following 8 equations hold? Note that ...
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1answer
276 views

Multiplying to reverse digits

Today I noticed that $294$ is a multiple of $49$, which is the last two digits of $294$ reversed. How many other numbers have this property? That is, how many three-digit numbers have a factor which ...
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683 views

What is the probability that all the bullets will be destroyed?

A gun shots bullets with different speed each second. The bullets form a straight line. The bullets keep their speed (not getting slower or faster). But if 2 of the bullets collide, 2 of them are ...
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1answer
294 views

H-one-one-oneycomb

        What path could a honeybee follow to fill all cells with honey, beginning and ending at the center and visiting every cell exactly once? At first the only ...
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5answers
1k views

A few word puzzles 1

Here are some short word puzzles. 1) What's a not uncommon 7 letter word containing all 5 vowels and "s" and one other consonant (not necessarily in order)? 2) What's a common one syllable word, ...
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3answers
598 views

Gambling with the leading digit of $2^n$

Your gambling friend has come to stay with you and offers to play a game with you as many times as you wish: He chooses an integer $x$ between $1$ and $9$ inclusive, and makes a wager of $\$1$ with ...
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6answers
708 views

What is the Key to Good No-Computers Puzzles?

Question What advice, strategies, keys, or elements would you suggest for creating challenging puzzles that aren't (reasonably) computer soluble? Details I'm a programmer, so I can appreciate the ...
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5answers
789 views

The distance between David and Eric

Alice and Bob are looking at each other, both turn $10$ degrees and now they both can directly see Claire. If they continue turning in their same directions before, Alice will directly able to see ...
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3answers
594 views

In honour to 2004

222444 is the smallest number that is divisible by 2004 and only contains the digits 2 and 4. What’s the next number that has the same properties? Hint:The number is 11 digits long.
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2answers
306 views

Hand tiling puzzle demonstrating Eisenstein triple $c^2 = a^2 -ab + b^2$

An Eisenstein triple is related to 60 degree triangles and a special case of the cosine law. But we need not worry about that except to note that a specific example of an Eisenstein triple is $7^2 = 5^...
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4answers
483 views

The broken wheel

In a regular polygon, we can connect six of the vertices to form a convex hexagon. I construct a hexagon by picking six vertices out of a regular $n$-sided polygon. In this hexagon, if you connect the ...
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2answers
637 views

A risky investment

I invested $1000 into shares. On the first day the share price went up by 10%. On the second day it went down by 10%. This process continued - the share price would go up by 10% on odd days and down ...
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2answers
392 views

Scanned Magazine Comics

This drawing was sent to me by a friend a few years ago. He said it is a kind of Mystery Case File but what to find is up to me figure them out. Is there something to find here?
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453 views

Alphametic as protest #2

Riddles for all. Since my latest alphametic as protest got a good feedback but my riddle as protest did not, I decided to stick to what works and added a new alphametic as a protest for the riddle ...
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4answers
700 views

Unusual letter combinations 2

I really liked this puzzle so I made my own version of it! I'll give you an unusual set of letters which are present consicutively in one* word in the English language (and possibly its derivatives, ...
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2answers
1k views

The magic of the primes

A mathematician, a physicist, and an engineer found themselves caught in an ancient anecdote. Lacking a chemist to brew them an anecdote antidote, they fell to arguing over which of them was to be the ...
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1answer
700 views

A B C in close knit relationship.. Who are they?

Find these closely knit numbers examining their relationships. A, B, C are distinct positive integers. AB, AC are concatenated Numbers. Given: 1 / AC = 0.0BC0BC0BC...... 1 / BC = 0.0AC0AC0AC......
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3answers
365 views

How can 15 become 3?

This is not a mathematical puzzle. How can 14 become 7? 10 becomes 1, but can also become 2. 13 becomes 8, and 8 becomes 10. 6 stays as 6 under this thinking. Hint 1: Since answer was found, OP note:...
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1answer
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Hangman- No misses left

**** No programs allowed. You must find the answer using your own brain. **** Your hangman game allows for 9 misses, but on the 10th miss, you're hanged! You don't want to be hanged. The letters ...
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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
368 views

Square Spin #4: Rude Awakening

Square Spin History: #1>#2>#3>#4 New Rule This puzzle introduces a new square type: Lonely squares (Ly) Lonely squares This type of square contains a box and it is the exact opposite of ...
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1answer
153 views

These Two Cubes are The Only Ones That Are All Pure Prime..name them

Given: CU and BBUE are concatenated Cubes with all prime digits B, C, U, E. Which are these two Unique Cubes?
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3answers
564 views

Ambiguous Grids

After six to eight weeks of waiting, your Shmikoli™ Ambiguous Grid Deduction Puzzle Set has finally arrived! You tear into the box only to discover that the instructions are missing. You shouldn't ...
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1answer
1k views

Christmas Sudoku

CHRISTMAS IS COMING!!! And to celebrate, here is a Christmas related sudoku: *A friend gave this to me and it took a long time for me to solve it. Thaks to @GentlePurpleRain for providing an updated ...
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2answers
203 views

Nebulosity alphametic

Every letter stands for a digit in decimal representation, different letters stand for different digits: ...
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2answers
277 views

Another follow the path of relation through the grid

Inspired by Galen's series of puzzles...there is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-...
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3answers
314 views

Holiday cookies word attrition [humans only]

I am inspired by the story of the boy who came upon an assortment of holiday cookies beautifully arranged on a platter. The boy quietly helped himself to a cookie and artistically rearranged the ...
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1answer
379 views

Whose birthday is it?

A group of people have gathered for a birthday celebration. Their ages are related as follows: The product of the 1st person's and the 2nd person's ages is $311\frac{2}{3}$ plus the 3rd person's age. ...

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