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Questions tagged [no-computers]

A puzzle designed to be solved without using calculators, online decoders or computer programming.

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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|} \...
48
votes
2answers
5k views

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 ...
46
votes
2answers
2k views

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 ...
46
votes
1answer
1k views

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 ...
41
votes
1answer
1k views

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 ...
40
votes
5answers
3k views

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 ...
39
votes
2answers
2k views

A simple nonogram

Solve the nonogram.                   (Click for a larger version.)
38
votes
4answers
2k views

Five Slitherlinks

Solve five Slitherlinks, each with a unique solution. Please say a word regarding (or show an image depicting) each solution method.
36
votes
1answer
1k views

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.....
35
votes
5answers
3k views

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?)
34
votes
11answers
8k views

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 ...
34
votes
1answer
2k views

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. Above you see a position where white is obviously on the ...
31
votes
6answers
2k views

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 ...
30
votes
4answers
2k views

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 ...
30
votes
1answer
2k views

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 ...
30
votes
2answers
2k views

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,...
29
votes
1answer
1k views

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 ...
28
votes
8answers
5k views

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 ...
27
votes
3answers
3k views

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, ...
26
votes
2answers
2k views

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 ...
24
votes
5answers
4k views

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 ...
24
votes
7answers
3k views

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 ...
24
votes
5answers
2k views

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 ...
21
votes
3answers
3k views

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 ...
20
votes
2answers
750 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 ...
19
votes
2answers
962 views

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 ...
19
votes
3answers
2k views

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 ...
19
votes
3answers
2k views

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
votes
1answer
2k views

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, ...
18
votes
4answers
1k views

A mazegic square

So you like mathematical diversions? Here's something new for you then ...
18
votes
2answers
709 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 ...
18
votes
2answers
2k views

Someone has vandalised this long division. Can you reconstruct it?

Oh dear, someone has vandalised this long division. They've replaced every digit either with a wrong digit or a hyphen. Your task: reconstruct the entire thing. There's no remainder. Please show ...
18
votes
2answers
1k views

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 ...
18
votes
2answers
2k views

Math logic Triangle

Rules Arrange numbers from 1 to 15 to the white triangles. A op B = result Green triangle means 2 numbers of its side are adjacent numbers. (-) means find the difference (/) means divide the bigger ...
17
votes
10answers
7k views

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 ...
17
votes
6answers
3k views

Nobody likes this compound word

This compound word, that no-one likes, is made up of 3 consecutive words. Also made up of 2 consecutive words. Also the prefix and suffix are identical words Uses only 3 consonants. ...
17
votes
2answers
2k views

We are two immediate neighbors who forged our own powers to form concatenated relationship. Who are we?

Our concatenated number is $ \overline{ABAC}, $ where $ A, B, C $ are all positive digits (1 - 9). Our relationship is $$ \overline{ABAC} = A^A + B^B + A^A + C^C $$ Who are we?
17
votes
5answers
2k views

Second-rate spelling

Find the longest word which can be spelled with the second letters of a group words in alphabetical order. An example with incomprehensible (16 letters): a...
17
votes
2answers
1k views

Oh, woe is me, the creature's back

Oh, woe is me, the creature's back to give me certain heart attack! He's plucking words and shifting glyphs. What sort of devilry is this? I love the gates of hell; I’m kind of a rod (6) The apple ...
17
votes
2answers
712 views

Color Logic - Find the rule

Find the rule specified in the image below. Taken from Caterpillar Logic, now the app is gone.
17
votes
3answers
298 views

Pairs of Pairs of Pentominoes

Split the 12 pentominoes into three sets of four. Can you pair up pentominoes so that each set makes two of the same shape? For instance, one of your three sets could look like this: That uses the L,...
17
votes
1answer
1k views

The Lord of the Puzzles

In 1904 (at the age of 12) J.R.R. Tolkien sent a "puzzle letter" (pictured below) to a family friend; Father Francis Morgan. What does it say? Obviously it would be trivially simple to google the ...
17
votes
1answer
348 views

2 Knights tied together in a dangerous maze

2 knight pieces of the game chess were trying to find their way to freedom, while being tied together with a small rope. It was so small that it forced them to be placed in adjacent squares at all ...
16
votes
5answers
2k views

Divisible by seventeen

Determine the smallest integer $n \geq 0$ for which the decimal digit sum of n is a multiple of 17 the decimal digit sum of $n+1$ is a multiple of 17. No computers! The puzzle has a nice direct ...
16
votes
1answer
692 views

Complete the world's longest self-documenting sentence

Complete the following by filling in the blanks with written numbers to create the world's longest self-documenting sentence. ...
16
votes
1answer
525 views

Riley Riddles in Reverse, batch 2

"post some more sometime :)" -- user @Dragonrage in the comments of Riley Riddles in Reverse Here's another batch of "inverted" Riley riddles. These still work exactly like the ones before: You ...
15
votes
9answers
4k views

Perfect Squares!

A question was asked in a mental ability test yesterday. Write four distinct numbers with these properties: 1. Sum of each pair is a perfect square. 2. Sum of all four is also a perfect ...
15
votes
6answers
1k views

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 ...
15
votes
9answers
4k views

Solitaire Chess

A friend of mine got me Solitaire Chess for Christmas years ago. I set up the board below. Is it possible to solve it? If so, what is the solution? (No programs allowed- Use only your brain.) Rules: ...
15
votes
2answers
1k views

What's the missing pattern? 3x3 grid, dot pattern

What is the missing piece to this pattern? Got it as a quiz at work - no one here knows what it is!