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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72
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2answers
6k views

Oh dang, I have to change my whole answer!

One day, you enter your math classroom. On the board, there are the words POP QUIZ. Dang it! Was it about fractions? you knew you were bad with fractions. You look down. $\begin{array}{|cc|} \...
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Sudoku like you've never seen it before

I've spent this week trying to create a difficult logic puzzle which is a combination of two Sudoku varaints, 'Samuari Sudokus' and 'Pseudokus', and this combo is unlike anything you can find online. ...
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A 16 Clue Sudoku Puzzle (but the kings can't be in check)

An entry in the 19th fortnightly challenge... Above is a 9x9 "chess" board with some pieces already laid out, your goal is to fill the board completely, following standard Sudoku rules (i.e. every ...
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Six pyramids in a cube

This question is from the German mathematics competition Känguru der Mathematik. In this competition students have to solve 30 mathematical tasks like this in 90 minutes without calculator. Actually ...
50
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1answer
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re-re-reCAPTCHA

Last Friday, I was feeling a bit sad because I hadn't earned much rep recently, so I decided to try this awesome sock puppet thing everyone's been raving about. I logged out of my normal Puzzling ...
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Can you stop the rambling rook?

This is a chess puzzle someone showed me a long time ago. If you already know this puzzle please give the others a chance to solve it first. This puzzle was originally created by Otto Gallischek and ...
43
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4answers
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Five Slitherlinks

Solve five Slitherlinks, each with a unique solution. Please say a word regarding (or show an image depicting) each solution method.
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A simple nonogram

Solve the nonogram.                   (Click for a larger version.)
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1answer
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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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5answers
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TRUMP to BIDEN : This transition won't be easy

Can you change the word TRUMP to the name BIDEN in 10 steps or less by changing one letter at a time? Each change must result in a valid word from MW dictionary. No proper nouns, abbreviations or ...
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Unusual letter combinations

This is an entry in the Fortnightly Topic Challenge #41: Short and Sweet. English spelling is very strange. Sometimes you encounter words with letter combinations that would seem entirely ...
41
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1answer
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A cubic colored pyramid

While preparing the next puzzle for publishing, I decided to encrypt the file to protect it, but something went wrong or maybe I entered the wrong command because the puzzle was encrypted, yes, but ...
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Word that is fun. Nine and one

Starts with a name, ends with a name Starts with a charge, ends with a charge Starts with an element, ends with an element Would be fun to guess this one! (May be more than one?)
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1answer
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Riley Riddles in Reverse

In the all-famous Riley riddles, you have to guess one word from clues about its prefix, infix and suffix. Here, instead, You get three words. You must find one solution word that you can attach.....
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too easy puzzle? Try it first!

Arrange the numbers $1$ to $9$ to replace letters $A$ to $I$ so: $(A+B+C+D)-(E+F+G+H) = I$ Too easy? Too many answers? Try it first! Then explain why.
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Ten girls around a table

Ten girls are sitting around a table. Each of them picks a real number and whispers it to the two neighbors immediately to the left and to the right. (Hence: each girl communicates one number, and ...
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3answers
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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?
33
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1answer
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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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A triangle formed of three letters

Consider a downward-pointing triangle of letters X, Y, and Z formed by the following algorithm. Start with a sequence of 10 letters each of which is X, Y, or Z. Under each row, construct the next row ...
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Breaking the record

There is a record whose value is expressed by a natural number. (The value is strictly discrete, not only continuous and then rounded to a natural number.) However, after the record is once ...
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1answer
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Computation without a computer

In the number $(1+\sqrt{3})^{2015}$, what is the 224th digit after the decimal point? You may NOT use a calculator, computer, or any electronic aid to answer this question. Only pen(cil), paper, and ...
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Parallelisation

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids Puzzlers, I am presenting a set of six duo-grids! Of course, I need to tell you how they work - you are given a grid. Looking at it,...
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1answer
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A Secret Job . . . but what is it?

Mr. Peters, a freelance muscle-for-hire sort of fellow, had been manning his desk for days now waiting for something to do when at last the phone rang. A job! The nerdy sounding person on the other ...
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3answers
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Uh oh, the propeller fell off

I was rummaging through a trunk in the attic when I found this vintage game. It is some sort of pinwheel or propeller mounted on a board. The propeller has a cryptic series of letters painted on it, ...
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8answers
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Another Easy Mate in 1

Standard chess rules apply, the board is not rotated (i.e. white pawns move upwards), no lateral thinking is needed. Simply find the one move for white which mates the black king. This puzzle was ...
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The No-Straight Maze

Consider the following maze. You can walk on the black lines, and your aim is to go from the green at the maze's bottom to the red on the left side. However, each time you reach an intersection of ...
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RIDDÅL - another unfinished flat-pack puzzle

This is an entry to the 19th Fortnightly topic challenge Yesterday I got a package in the mail. Attached to its top was a letter: Dear Alconja, That's strange, I thought... Must have gone to the ...
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Some numbers are more equivalent than others

[Second part and bounty challenge appended in May 2020]           ALL ANIMALS ARE EQUAL    BUT ...
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Superhero words!

Quietly walking among us are words which are actually superheroes in disguise! Just as Diana Prince spins around to become Wonder Woman, some seemingly ordinary words can spin around to reveal their ...
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Like totally amazing interchangeable sister outfit accessory swapping or whatever

OMG, me and my sister are like total BFFs and we share clothes like all the time! We soooo have the same sense of style and we borrow stuff from each other like every single second! We don't even ...
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4answers
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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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What number is that ? Asks Grandpa

"So here is a number between 1 and 60" Says Grandpa "If you take its WORD anagram and subtract this number you will get Anagram of the number - number > 5 What is that number"? "So it is the ...
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3answers
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Find 77777 solutions

You have three flat pieces, as shown: Arrange them flat, without overlap, such that the shape formed by the black parts is congruent to the shape formed by the white parts. Rotation and reflection ...
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5answers
809 views

Square Spin #1: Sun and Moon

Defining Square Spin Lets play a game! The aim of this game is to transform one image into another using the least amount of moves possible. Here is what a move consists of: ...
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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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1answer
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Farmer needs to get his word across the river

In the spirit of the classic river-crossing puzzles: ...
20
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1answer
782 views

The little bee buzzes around the flower garden

Watch the little bee buzz around the flower garden. Pay particular attention to how he picks up or drops off pollen (i.e., a single letter) at each flower. Notice: — The little bee visits each ...
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2answers
812 views

Honeydripping around the clock

      What path could a honeybee follow, beginning and ending at top center, visiting every empty cell exactly once and dripping 2 drops of honey into the last cell? Start ...
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4answers
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A mazegic square

So you like mathematical diversions? Here's something new for you then ...
19
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2answers
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Self-intro to mo-Roman numerals

Here come mo -Roman numerals — just like Roman numerals, only mo’ so.   (Explained as we go.)   What number can spell itself in two different ways ...
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3answers
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We feast in Hell's kitchen, we swim through the deep

We feast in Hell’s kitchen, we swim through the deep, we wait in the shadows for printers to sleep. At midnight we come and we jumble your prose. We pluck out your words because god only knows! And ...
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Which two houses didn't get any mail that week?

Postman delivers the mail in the small village. This village has exactly ten houses, numbered from 1 to 10. In a certain week, he did not deliver any mail at two houses in the village but at ...
19
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1answer
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Today is a sad day

Today is a sad day - Today, it was supposed to be my big day to shine! But unfortunately that is no longer the case. I have heard from others here that puzzle-making is a great way to drown out one's ...
19
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2answers
766 views

Step into the Octagram

The diagram below shows a partially-filled "octagram". Step into it, if you dare! At every vertex in a long word. Flowing into every vertex are two short words. Anagrammed together, these two short ...
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2answers
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Sudoku in the third dimension (3D Sudoku)

People seemed to enjoy my last Sudoku variant puzzle - Samurai Pseudoku, so I spent this week making another! This one is going to require using logic you've never used before... The last one was a ...
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2answers
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Three for the price of one

While browsing through your local puzzle store, you see something you can't resist: a box which promises two grid deduction puzzles for the price of one! The vendor explains that the box contains a ...
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1answer
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Make numbers 0 - 11 using the digits 2, 0, 1, 8; BUT

... seriously, this is definitely NOT that "kind of puzzle"! ;) So let me create this puzzle to freshen you up! It is inspired by a meta question: Yet another 2018 puzzle. Put the digits 2, 0, 1, ...
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Fully-Firstable Anagram Sets

Okay, first let's define some terminology: Anagram - Oh come on, how are you on Puzzling.SE if you don't know this one? Anagram Set - a list of words that are all anagrams of eachother, e.g.: ACTS ...
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A word pronounced like letters

Can you give me a word that when pronounced, sounds exactly like pronouncing some of the letters of the alphabet. For example The word TEEPEE sounds exactly like the letters T and P so TP, just as ...
18
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2answers
841 views

Color Logic - Find the rule

Find the rule specified in the image below. (Where I got it)

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