Questions tagged [no-computers]
A puzzle designed to be solved without using calculators, online decoders, or computer programming. Using a computer to type and post the answer is allowed; the spirit of this tag is to make people solve the puzzle on their own.
797
questions
9
votes
7
answers
757
views
Recover book titles and suggest more books
I am working on a series of book-trivia puzzles. Given an excerpt from the book directly mentioning the book title, players are asked to fill in the title.
Example
Given the excerpt
...now we ...
- 745
15
votes
3
answers
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 ...
- 2,346
75
votes
2
answers
7k
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|} \...
- 3,625
6
votes
2
answers
273
views
Square-root of CAREER alphametic
Every letter stands for a digit in base-10 representation,
different letters stand for different digits,
and leading digits are always non-zero.
$\sqrt{CAREER} \,\, = \,\, RUT $
Which digit does ...
- 11.7k
36
votes
12
answers
9k
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 ...
- 45.4k
8
votes
3
answers
373
views
Flock of Geese alphametic
In each of the following three alphametic puzzles, every letter stands for a digit in base-10 representation, and different letters stand for different digits. Leading digits are always non-zero.
<...
- 11.7k
17
votes
5
answers
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 ...
- 8,304
5
votes
3
answers
277
views
French alphametic (corrected)
This is the corrected version of puzzle
French alphametic (misspelled)
Every letter stands for a digit in base-10 representation,
different letters stand for different digits,
and the four ...
- 11.7k
0
votes
2
answers
306
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 ...
- 11.7k
4
votes
2
answers
240
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 ...
- 11.7k
8
votes
2
answers
224
views
Nebulosity alphametic
Every letter stands for a digit in decimal representation,
different letters stand for different digits:
...
- 11.7k
6
votes
1
answer
167
views
Wheat field alphametic
Every letter stands for a digit in base-11 representation,
different letters stand for different digits:
WHEAT
+ FIELD
------------
FARMER
...
- 11.7k
9
votes
2
answers
332
views
Happy days alphametic
Every letter a decimal digit, different letters for different digits:
HAPPY
HAPPY
HAPPY
+ DAYS
----------
AHEAD
Which digit does each letter ...
- 11.7k
6
votes
3
answers
2k
views
Baseball games alphametic
Every letter a decimal digit, different letters for different digits:
BASE
+ BALL
--------
GAMES
Which digit does each letter represent?
- 11.7k
15
votes
4
answers
489
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 ...
- 25.7k
5
votes
2
answers
795
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 ...
- 1,274
5
votes
1
answer
260
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 ...
- 45.4k
-12
votes
1
answer
648
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 ...
- 14.4k
6
votes
1
answer
201
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:
...
- 45.4k
10
votes
4
answers
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 ...
- 45.4k
-10
votes
2
answers
583
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, ...
- 14.4k
49
votes
2
answers
4k
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 ...
- 18k
9
votes
6
answers
943
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 ...
- 11.6k
6
votes
7
answers
4k
views
Find the longest string of words such that the (4 letter) end of one word is the start of the next [closed]
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) ...
- 8,079
5
votes
1
answer
891
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 ...
- 11.6k
12
votes
1
answer
4k
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 ...
- 116k
8
votes
2
answers
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 ...
- 116k
8
votes
4
answers
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 ...
- 116k
4
votes
3
answers
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 ...
- 2,131
17
votes
1
answer
768
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.
...
- 8,914
13
votes
2
answers
536
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 ...
- 10.1k
7
votes
2
answers
841
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 (only ...
user13180
2
votes
1
answer
358
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 ...
- 4,569
21
votes
2
answers
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 all ...
- 4,569
11
votes
5
answers
1k
views
Knight on the keyboard [closed]
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). ...
- 5,878
17
votes
1
answer
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 ...
- 5,280
5
votes
3
answers
382
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 ...
- 17.4k
14
votes
3
answers
641
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 ...
- 32.1k
3
votes
1
answer
783
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 ...
- 1,330
3
votes
2
answers
1k
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 ...
- 17.4k
6
votes
1
answer
568
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 ...
- 12.6k
-1
votes
3
answers
55k
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.
- 151
8
votes
2
answers
798
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 ...
- 116k
17
votes
9
answers
5k
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:
...
- 17.5k
8
votes
1
answer
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 ...
- 17.5k
7
votes
1
answer
1k
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 ...
- 32.1k
31
votes
1
answer
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 ...
- 116k