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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9
votes
2answers
296 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
1answer
164 views

Wheat field alphametic

Every letter stands for a digit in base-11 representation, different letters stand for different digits: WHEAT + FIELD ------------ FARMER ...
4
votes
2answers
216 views

Neil Armstrong and Buzz Aldrin alphametic

Every letter stands for a digit in decimal representation, different letters stand for different digits: MEN + CAN = REACH - MOON Which digit does each ...
0
votes
2answers
283 views

French alphametic (misspelled)

The following puzzle has a spelling mistake: DOUCE should be DOUZE. The correct version is: French alphametic (corrected) (Surprisingly the faulty version allows feasible solutions.) Every ...
0
votes
2answers
192 views

Simplist proof you have for the Monty Hall Problem [closed]

This sounds simple. What is the easiest solution to the Monty Hall problem you have which does not use listing out every probability and also requires you use algorithms? Also, no research or ...
15
votes
3answers
2k views

A weird pocket calculator

A weird pocket calculator has a numerical display (for digits 0-9) and only two buttons, inscripted $\boxed{D+}$ and $\boxed{D-}$. The first button doubles the displayed number and then adds 1. The ...
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 ...
15
votes
4answers
432 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
759 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
229 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 ...
4
votes
1answer
168 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: ...
2
votes
1answer
640 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 ...
-10
votes
2answers
517 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, ...
5
votes
1answer
823 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 ...
8
votes
6answers
707 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 ...
8
votes
2answers
1k 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 ...
12
votes
2answers
452 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 ...
16
votes
1answer
717 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. ...
2
votes
1answer
346 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 ...
5
votes
3answers
357 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 ...
6
votes
1answer
530 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 ...
14
votes
3answers
562 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 ...
0
votes
0answers
173 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 ...
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 ...
31
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 ...
7
votes
1answer
815 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 ...

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