The Stack Overflow podcast is back! Listen to an interview with our new CEO.

Questions tagged [no-computers]

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

Filter by
Sorted by
Tagged with
6
votes
1answer
157 views

Wheat field alphametic

Every letter stands for a digit in base-11 representation, different letters stand for different digits: WHEAT + FIELD ------------ FARMER ...
9
votes
2answers
257 views

Happy days alphametic

Every letter a decimal digit, different letters for different digits: HAPPY HAPPY HAPPY + DAYS ---------- AHEAD Which digit does each letter ...
6
votes
3answers
942 views

Baseball games alphametic

Every letter a decimal digit, different letters for different digits: BASE + BALL -------- GAMES Which digit does each letter represent?
15
votes
4answers
397 views

E's-y Word-Square Fill-in

Not necessarily easy, but "'E's-y"! For each word square below, the Es have been filled in for you. Your task is to complete the rest of the square using only ...
5
votes
2answers
711 views

I Was Told It Would Explode

Story: There is a line of bombs, all over a building. You are the bomb defusal expert, and you are the one everyone is counting on the save the city, for as if any one of the bombs go off, you, and ...
5
votes
1answer
206 views

Crossing out a digit

Find the largest integer $N$ whose decimal representation has the following properties: The rightmost digit in the decimal representation is not $0$. There exists a digit $d$ in the decimal ...
-13
votes
1answer
518 views

Social networking “party” system

A party is a group chat, the only difference being there's a "leader" (this is the person who started the chat) In these parties, there can only be 5 maximum users, this includes the leader. In ...
4
votes
1answer
155 views

Increasing rows and columns

Cosmo has arranged the integers $1,2,\ldots,49$ in a $7\times7$ table, so that in each row (left to right) and in each column (top to bottom) the entries occur in increasing order. Questions: ...
10
votes
4answers
2k views

A sloppy calculation

Little Johnny Red forgot to write the multiplication sign between two 3-digit numbers $x$ and $y$ and simply wrote them as one number. When Johnny's teacher graded the homework, it turned out that the ...
-10
votes
2answers
493 views

Longest $Scramble Sentence$? [closed]

Before we begin, allow me to define what I call a Scramble Sentence, A Scramble Sentence is a grammatically correct sentence, where at least 1 other permutation, of the letters in the sentence, ...
46
votes
2answers
3k 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. This puzzle was originally created by Otto Gallischek and ...
8
votes
6answers
652 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 ...
4
votes
7answers
4k views

Find the longest string of words such that the (4 letter) end of one word is the start of the next

Here is an open-ended challenge. Find the longest series of English words such that the final four letters of word $n$ are the same as the first four letters of word $n+1$. Example (3 words) ...
6
votes
1answer
791 views

A Four Liner of my Own: I'm counting on you

With all the popularity of four liners lately, I figured I'd contribute. Since my recent riddles seem to have been too hard, I'll err on the side of ease this time. Determine what each line is ...
11
votes
1answer
3k views

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 ...
8
votes
2answers
983 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 ...
7
votes
4answers
1k views

Comparing exponents - no computers!

Which is larger, $99^{100}$ or $100^{99}$? Which is larger, $999^{1000}$ or $1000^{999}$? Or more generally, for $n$ any natural number: which is larger, $n^{n+1}$ or $(n+1)^n$? Please do not use a ...
4
votes
3answers
2k views

How is it possible?

I have been captured, then shot, framed and hung. But luckily, I am not dead. How is it possible? Disclaimer: this puzzle is inspired by real world observation, so no alien lifeforms, super heroes ...
16
votes
1answer
700 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. ...
12
votes
2answers
427 views

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 ...
7
votes
2answers
733 views

Password Cracking

You are trying to crack someone's password. You don't have any password cracking software, nor do you have time to get any. From sources unknown, you know that: A. The password is alphanumeric (...
2
votes
1answer
340 views

Reconstruct this multiplication to find the combination for the safe

You've solved it! No, wait a minute - you've solved the first step. You don't know the combination for the safe yet. All you know is that someone has helped you by using a pseudonym. Their name isn't ...
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 ...
10
votes
5answers
1k views

Knight on the keyboard

You are given a QWERTY keyboard, and are allowed to choose where you wish to start. You are only able type in the same way a knight is able to move on a chessboard (but in this case, on the keyboard). ...
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 ...
5
votes
3answers
339 views

What is the next word in this sentence?

WARNING: You could totally search online for this and find the answer. Note the no-computer tag. Yes, you can cheat and I wouldn't know. However, that's not nearly as much fun and you'd be trading ...
14
votes
3answers
508 views

Cross, Dot and Scalar Product

This puzzle may seem off topic; though the motivation and background is somewhat mathematically technical, its solution is purely combinatorial (and quite cute). In multivariable calculus, the main ...
2
votes
1answer
610 views

Guess the book character

His raiment was the color of the king of Doriath's cloak, But now is the color of the Spirit of Fire's prized creations. His weapon is from that which was betrayed by the Child of Twilight. His ...
3
votes
2answers
753 views

The Pirates and the Mangoes [duplicate]

A group of hardy pirates are sailing along when they encounter the Royal Navy of Lord Richard. The battle is long and vicious. Sadly, the pirate ship is sunk. The only survivors are five of the crew ...
6
votes
1answer
505 views

Lights in the theatre

A play of Romeo and Juliet is being held in the theatre tonight, hundred of people have been waiting this moment for months. Many people are currently working hard in the theatre to adjust the final ...
-1
votes
3answers
46k views

Use the numbers 8 6 4 2 = 25

Use the numbers 8,6,4,2 and the operators +,-,*,/ to get 25. You can use each number once. Each operator can be used once. The least number of operators you use the better answer will be.
0
votes
0answers
167 views

3 Gods Logic Puzzle [duplicate]

This logic puzzle can be found on the web so NO GOOGLING! You walk up to three gods. One always tells the truth, one always lies, and one randomly decides to tell the truth or to lie and does what ...
7
votes
2answers
727 views

Evaluate the nested square roots

Evaluate the following expression to 4 decimal places: $$\sqrt{1+2\sqrt{1+2\sqrt{1+\dots+2\sqrt{1+2\sqrt{2015}}}}}$$ where the number of square roots in the expression is exactly 2015. As per the ...
16
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: ...
8
votes
1answer
1k views

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 ...
7
votes
1answer
667 views

A Game with Strings and Coins

Alice and Bob play a game using the following arrangement of coins, which are joined by strings and hanging from the ceiling: $\qquad\qquad\qquad\qquad\quad$ The two alternate turns, with Alice ...
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 ...