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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How often does a digital watch show a palindrome?

A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward, such as madam or kayak. We have a digital watch showing the time HH:MM:SS as shown in ...
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Crossword gone overboard

This puzzle is part 24 of Gladys' journey across the globe. Each part can be solved independently. Nevertheless, if you are new to the series, feel free to start at the beginning: Introducing Gladys. ...
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756 views

Pythagorean triplets wheat field

A rectangular field has width $a$ and length $a+1$. We cut it into 3 triangles that all have integer side lengths. If all triangles have a different area, then what’s the minimum value of $a$? Please ...
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Digit sums of successive integers

For a natural number $x$ both, the digit sum of $x$ and the digit sum of $x+1$ are multiples of $7$. What is the smallest possible $x$?
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And now you see it II (the B side)

It amuses me that the word CANOES has been there in VOLCANOES all along. And URCHIN is barely hiding in the word LURCHING. And ASPIRIN is right there in ASPIRING. SISTER is in RESISTER. AKIN is in ...
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Dear Fellow PSE Users,

This puzzle is dedicated to all of you! Instructions There are 8 anagram questions below. In each question, you can rearrange the letters to find an answer, which is 2 English words that describe a ...
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1answer
406 views

Infinite Sequence based on Simple Rule

Using one simple rule, an Infinite Sequence has been developed. First 30 terms are given. Can you continue the sequence for at least next Ten Terms? Series continues from top left to bottom right. $...
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2answers
853 views

Delete a digit then sum

Take a number $(x)$, then create the complete list of the numbers formed by deleting single digits from its base ten representation $(d_1,d_2,...,d_n)$. If the sum of those new numbers equals $x$ we ...
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Hit the Bulls Eye with T in the Center

There are 3 Rings with “T” in the center. In each ring, letters are distinctly different - 16 in the outer, 8 in the middle, 4 in the inner rings. Hit the Bulls Eye by making sixteen different four ...
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A Halloween Chess Puzzle

Halloween is finally here, so I thought I'd do a theme puzzle! I love chess, and I wanted to do a chess puzzle... so... (It kind of looks like a jack-o-lantern, okay?) Black to move and mate in 5! No ...
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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 ...
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A mo-Roman sampler

    Pluck some relatively easy mo-Roman mini-puzzles while there’s relatively easy pickin’s. What two English words, taken as mo-Roman numerals, form the same number? ...
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Some Stratospherically Strenuous Sudoku

These three sudoku are particularly irksome, can you logically deduce the solutions to all (or any!) ...and provide your reasoning? They are all proper sudoku - each has a unique solution. They can, ...
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1answer
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No Halves Hath the Heptagram

Here is the heptagram: Rules are the same as for the octagram. However, the heptagram has the very nice property that all words are unique. I.e., as you go around, you will not encounter any ...
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Gone ortho-flogging

 Well played, Scratchy, you just took 8 shots on Hole 9 of Puzzlington Municipal Ortho-flog Course! As presented As flogged (solved) by you --------------...
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1answer
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Follow the path of relation through the grid #1

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-right corner of the grid. Each square can ...
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Maximise your gold!

You met a genie. He gets $150$ magic lamps out, which are numbered from $1$ to $150$. You have to colour each lamp red or blue. After colouring, the genie will count the number of triples $T$ of magic ...
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Want to go from MANILA to UGANDA

How do you get from the word MANILA to UGANDA in the shortest time? You can change up to 3 letters at a time to form a new 6 letter word which MUST be either a Country name or a Capital of a country. ...
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The Special Numbers

Let's try to find out the numbers satisfying the cryptarithms below; $ab=(a+b)^2$ $abc=(a+b+c)^3$ $abcd=(a+b+c+d)^4$ There are only 3 unique answers! Note: $a$,$b$,$c$,$d$ are all ...
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Find the three digit Prime number P from the given unusual relationships

$Given:$ P is a 3 digit prime number Q,R,S,T are distinct digits( 0 to 9 ) QRS is a concatenated number $Relationships:$ $P$ = $QRS + T$ = Reverse of $( QRS * T)$ Find P using just ...
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The Ultimate Typo

Here are four sentences that I made up. But I accidentally shuffled the characters in every column! Can you figure out what the original sentences were? ...
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368 views

Cannibalistic Words

Drawing from the word pool below, find the twelve Cannibalistic Words. (Note the no-computers and logical-deduction tags.) WILD _ _ ☐ _ _ _ _ ☐ PENS ☐ _ _ _ _ ☐ _ _ DEED _ _ _ ☐ ☐ _ _ _ BLED _ _ ☐ _ ...
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One year celebration

I've got notified a few days ago from PSE that my account on this website is 1 year old. So I thought about celebrating it (or commemorating it, because you all made me addicted to this) with a puzzle ...
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My Graph Theory Students

I have 18 students in my graph theory course this semester: Anne, Bernard, Clare, David,..., and Rachel. At the start of the course I asked them to draw the graph below, in which each of them is ...
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792 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 ...
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Two dead beans on a stone

Samuel Bean, a Canadian doctor, had a tombstone erected in Rushes Cemetery near Crosshill, Wellesley Township, Ontario, for his first two wives, Henrietta and Susanna. The original stone was carved in ...
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Alphabetical Sudoku

Who loves fish? Okay that might sound a bit weird but don't worry, I am still sane. Maybe. To answer the question you must complete the Sudoku below. A word will appear in the highlighted box which ...
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1answer
477 views

Resolve this Fibonacci Relationship

$Given$: $A$, $B$, $C$, $E$, $F$ are distinct digits varying from $1$ to $9$. $A$ is a Fibonacci number. $BB$, $BC$, $EF$ are concatenated Numbers. $Relationship$: $(A*BB)*(BC)^2$ = $(EF)^2- B$ ...
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Comparatortionist: The $M_Q$ Functor

The Problem At the intersection of mathematics, computer science, and insanity, we find the $M_Q$ functor${}^1$. $${M_Q} = {\Phi _{{s_1},{s_2}}}\left\{ {\begin{array}{*{20}{l}} {E \leftarrow {\Phi ...
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1answer
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Multibranched tree

The Furca Fractalis tree grows in a very special way. Starting with the trunk there are three possibilities to continue growing: It can split in two branches. It can grow one branch and one leaf. ...
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1answer
521 views

A broken mosaic of words

In this puzzle, you'll have to rebuild words using the "pieces" listed at the bottom and place them in the grid provided below. Some notes about this puzzle: The gray cells with the dotted border are ...
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1answer
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A Puzzling Cryptex

I was hanging out in the Puzzing.SE lounge (the beanbag chairs are heaven) when some random person walked up. They said, "I love this place! Would you try my puzzle?" Their puzzle was a cryptex (...
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This word is a name. Also a Surname

Starts with a place, ends with a place Starts with a number, ends with a number Starts with a surname, ends with a surname A word to the wise. Only one vowel- used twice. Can you guess,...
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1answer
190 views

This compound word is a fun thing

Here is an interesting compound word It has all the 5 vowels but used only once (no repeat of the same vowel) It has 4 consecutive words that include 2 names. It starts with a name and ...
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1answer
409 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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1answer
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An alphametic for René Descartes

The best known philosophical statement by René Descartes is "Cogito ergo sum" (French: Je pense, donc je suis; English: I think, therefore I am). ...
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KenKen Zen: A journey begins

Let us shy away from the materialistic opulence of 361- cell KenKen layouts (−9 to +9, squared).  Let us contemplate a modest KenKen journey, unburdened by gratuitously ...
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Use 1 9 6 2 in this order to make 75

I'm looking for a solution to make number $75$ with numbers $1$ $9$ $6$ $2$ in that order and the same rules as in Use 2 0 1 and 8 to make 67. Here a copy of those rules: You must use all 4 digits. ...
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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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7answers
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Fill in the boxes to get the right equation

Here is a math puzzle I had a little bit of hard time with No computers please There is a solution without inverting 6 to 9
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6answers
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Coke alphametic

The only thing I love more than Coke is numbers divisible by 73. I claim I have found a unique assignment of distinct digits $0,1,...,9$ to the symbols $ C, O, L,$ and $A$ such that $73$ divides the ...
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How many coins did Mrs. Jones have?

Mrs. Jones is celebrating her 43rd (Prime number) birthday. Over the years she has collected gold coins. The number of coins is a Prime number less than 100. She decides to give all the coins to her ...
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Here's another Color Logic problem

Find the rule specified in the image below. Note that the rule applies to each row independently so every "true" row is "true" by itself If you are confused about these, here's an easy one: Did you ...
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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 ...
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689 views

Three positive integers

Find the smallest possible value of $ab+c$, where $a,b,c$ are positive integers with $a+bc=2016$. (No computers! The puzzle has a nice direct solution.)
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646 views

Five Powers of Fives Produce Unique Pandigital Number…Solve for X..Tell me Y

Given: Y is a Pan-digital Number (no zero, 1 to 9 only) ending in 3. Pan digital number consists of all 9 digits 1 to 9..each digit occurring only once as is the case here. Last digit is given as 3 ...
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764 views

Happy 2017 Sudoku

This is a simple Sudoku. The only thing different from a regular sudoku are the symbols used: HAPY2017*. The snowflakes (a.k.a. asterisk) are like any other character. Wishing you a Happy New Year ...
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Ziggy - Make a square from 8 polyomino pieces

A few years ago I created a small packing puzzle that I'd like to share here today. The puzzle is based on the fact that $1+2+3+4+5+6+7+8 = 6^2$. It consists of 8 zig-zag polyomino pieces, ranging in ...
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1answer
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What are these numbers?

A simple (I think) alphametic puzzle $\small{MADMEN = (M+A+D+M+E+N)^{((M+E+N) - (M+A+D))}}$ M,A,D,E,N are different (no repeats) positive integers between 0 and 9 and of course the 2 Ms are the ...
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1answer
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Gaby´s Puzzle (Primes Around a Circle)

To keep them busy during lockdown, Gaby asked her children to find a way to place the first sixteen primes (2 to 53) around a circle so that either the sum or difference (or both) of any two of them ...

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