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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36
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1answer
2k 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.....
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2answers
329 views

Barrel - Part 5

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Title based on this xkcd. This is a continuation of Barrel - Part 1, Barrel - Part 2, Barrel - Part 3, and Barrel - Part 4, but this ...
4
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1answer
324 views

A challenging Magic Square

Find a 3x3 Magic Square where each row, column and both diagonals result in positive number 9 You are allowed any of the 4 math operations : add, subtract, multiply or divide. NO OTHER OPERATIONS ...
13
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1answer
423 views

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 ...
6
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1answer
186 views

Tiling a rectangle with an odd number of Y pentomoes

Follow-on from Tiling a rectangle with just the Y pentomino Two questions: Find the smallest rectangle that can be tiled with an odd number of Y pentominoes, or prove it impossible Find the smallest ...
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3answers
610 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. ...
5
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5answers
1k views

Color Logic problem 3

Find the rule specified in the image below. Make sure the rule fully satisfies. Part two and one
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2answers
2k views

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 ...
18
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2answers
829 views

Color Logic - Find the rule

Find the rule specified in the image below. (Where I got it)
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2answers
660 views

A very evil cipher

A very evil tyrant locks you in a very evil cellar in a very evil castle. Every day he brings you a bit of soup and a bit of bread with a message he says, "It's the code but you have to decipher it ...
3
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2answers
4k views

Strategy for 2x3 Sliding Puzzle

Here's an instance of a $2$x$3$ sliding puzzle: The $2$x$3$ sliding puzzle is just a smaller version of the well-known 15 puzzle. Many guides exist on solving the 15 puzzle, and there are strategies ...
7
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2answers
342 views

How many dates are ambiguous across the Atlantic?

The Day/Month/Year date system commonly used in Britain (and much of Europe?) and the Month/Day/Year system commonly used in the US can lead to confusion when, for example, we write 9/3/2018 for the ...
2
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1answer
267 views

A magical operation #2

Quick reminder of what is a magical operation A magical operation on a particular number (not ending by 0) is the addition of this number with his symetrical number. For example the magical operation ...
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3answers
1k views

Let's go back in time!

Okay, so below are a handful of ciphers. They're pretty easy to identify, ranging from simple substitution to complicated binary. Some may have the keyword given others you have to solve. Now you're ...
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3answers
2k views

A magical operation

A magical operation on a particular number (not ending by 0) is the addition of this number with his symetrical number. For example the magical operation for 2018 would be 2018 + 8102 = 10120. Let ...
7
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1answer
2k views

Find the missing numbers in the magic square

The following is a magic square: each row, column and diagonal add to 34, all of the numbers 1 to 16 appear exactly once. Find the missing numbers.
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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, ...
6
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2answers
247 views

Challenging 15 rectangle tiling problem

This will test you, a computer will definitely help. Just one set of $1:2$ aspect ratio rectangles this time, but $15$ of them. Short side only is listed. The challenge is to arrange them into a ...
6
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3answers
465 views

How many 5+ letter words can you find?

NYT does a word hive in every Sunday edition, and I quite enjoy it, so I decided to make my own, using the same rules. Check it out: If you're unfamiliar, here are the rules. You may only use the ...
4
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1answer
170 views

Slightly bigger 1:2 hand tiling, getting a little harder

Pretty sure an expert hand tiler would be able to find this. Please post a spoiler only if you hand tile it... Tile a $60\times60$ square with $1:2$ rectangles of sizes ...
4
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2answers
273 views

Trickier hand tiling

This should be a little trickier. Using $20$ rectangles of aspect ratio $1:2$, make two squares. Use sizes 2,3,7,12,16 in both squares. And split this list among ...
4
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1answer
200 views

Two similar hand tiling puzzles

Make a square from each of these lists of aspect ratio $1:2$ rectangles 1, 4, 5, 6, 7, 9, 11, 12, 13, 14, 15, 17 ...
3
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1answer
120 views

Dissect a square into 1:2 non-congruent integer-sided rectangles

(Similar to the recent 3:1 and my 3:2 rectangle question) Tile a square completely with rectangles which have aspect ratio 1:2, integral side lengths and all different sizes. In other words selected ...
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2answers
3k views

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? ...
10
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1answer
406 views

So many names in this place

The spelled name of this one word place is kind of interesting It has within its name: Three first names One last name One name of a country One name of a Province/State/Territory One ...
3
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1answer
126 views

Hand tiling puzzle 2

Here's another set of polyominoes (sizes 4,5,6,7,8,9,10) that you can print and cut out. As before, the two smallest (same pieces as previous version) make a 3x3. The rest of the pieces are different. ...
8
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3answers
216 views

Hand tiling puzzle

Here's a set of polyominoes (sizes 4,5,6,7,8,9,10) that you can print and cut out. You can use the two smallest to make a 3x3. Nice easy one to get you started. Add a piece to make a 3x5. Add another ...
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5answers
2k views

Optimal Money-Saving on the NYC Metro

You are on vacation in New York City. You didn't bring your car, and it's currently around $-50^\circ C$, so it's probably a good idea to take the NYC metro subway to move around. You need a metro ...
6
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1answer
219 views

How many dimensions?

You have $n+1$ points in $n$-dimensional Euclidean space, such that the mutual distance between each pair of points is the same. Now imagine an $n$-dimensional generalization of a sphere, such that ...
9
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2answers
671 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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10answers
10k 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 ...
9
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1answer
264 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 ...
28
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8answers
6k 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 ...
5
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4answers
848 views

Word list: 2 consonants 2 vowels

Original 4 letter word Two consonants Two Vowels All next words use the exact same 2 consonants and exact same 2 vowels. Order not important Next word 5 letters Same 2 consonants same 2 vowels ...
12
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1answer
311 views

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. ...
10
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1answer
524 views

An incomplete set of numbers

Here's a fun math thing: Imagine building a set of non-negative integers, starting with zero. As you check increasing numbers, you add it to the set if doing so does NOT create a subset of three ...
11
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8answers
2k views

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 ...
18
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2answers
920 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 ...
3
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2answers
165 views

Polygon neighbors

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 ...
49
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2answers
6k 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 ...
6
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3answers
415 views

Lucky Lottery Tickets

Six-digit lottery ticket numbers are considered lucky if the sum of the first three numbers is equal to the last three. Eg. 123204, 871529... Prove that all possible lucky numbers added together is ...
7
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2answers
907 views

Triangle with incircle [closed]

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 ...
10
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1answer
227 views

Irrationality in the balance

Sensibilly -T ™ scales were out of stock, so Gramazon filled the order with a lousy Lopside® from Irreturnable Irrationals International, Inc.73205080...  How ...
13
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3answers
413 views

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 --------------...
8
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5answers
786 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 ...
11
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1answer
1k views

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 ...
4
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7answers
348 views

Sum of three six digit numbers

This puzzle is a variation of a 3 digit addition puzzle I saw recently. A , B , and C are positive integers between 0 and 9. A,B and C are different integers Six digit numbers formed using A,B and ...
4
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4answers
2k views

Three words with three animals

Can you give me at least 3 ( I found 4 so far) Five Letter words with at least 3 animal names spelled in them? No anagrams (rearranging letters). The 3 animal names must be in ONE WORD. Find 3 ...
4
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6answers
1k views

Tom's mysterious alphanumeric character

Tom: I drew a mysterious alphanumeric character and showed it to Harry. Dick: Harry, was it a letter or a number? Harry: I'm not sure! Dick: Assuming it was a letter, was it uppercase or ...
15
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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!

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