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.
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First digit of a large number
Can you find the first digit of
$2^{2^{2^{2^{2^2}}}}$?
Basically, it is $2$ to the $2$ to the $65536$ power.
You cannot use a computer, but are allowed to use a calculator.
Good luck!
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15
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2
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PSE Advent Calendar 2023 (Day 9): The Peppermint Twist
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2023. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
This puzzle ...
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4
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First digit of 3^2020
Inspired by
The last digit for 3^(2019)
Can you find the first digit of 32020 without a computer?
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1
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Ended up with 'empathise'
I started off with a one-letter English language word. For every step, I added one letter of my choice, and re-arranged the letters to make a new word. By the end, I had:
EMPATHISE
What was the word ...
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Minimum function optimization puzzle #4: Using negative numbers?
Previous puzzle
Take this puzzle of mine that I created around a week ago:
Take these 3 functions: $f(x):=x+8,g(x):=x^2-3,h(x):=\sqrt x$
Starting from $x=0$,$$\color{black}{\text{How many times will ...
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2
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Minimum function optimization puzzle #3: 3 functions
Previous puzzle
Take this puzzle of mine I created recently:
Let $f(x)=x+1$, $g(x)=x^2-1$, $h(x)=2x-4$. Starting with $x=0$ and applying these functions as needed, what is the minimum amount of times ...
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vote
1
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A Hidato, but with no given numbers?
I can be a bit evil sometimes. Today, I am going to give you a Hidato with no numbers! It gets worse: This puzzle is on a Mobius Strip Y[1] However, I will give hints as to what the numbers are, so ...
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Minimum function optimization puzzle #2
Previous puzzle
Take this puzzle of mine I created about an hour ago
Take two functions, $f(x):=x^2$ and $g(x):=x-3$. Starting from $x=0$ and applying these functions as needed, what is the minimum ...
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1
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1
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Is my solution to a mathematics puzzle I created the most efficient solution there is to it?
Here's a puzzle of mine that I created around 2 hours ago:
Let $f(x):=x^2$ and $g(x):=x-4$. Starting with x=0, what is the least amount of times you need to apply the functions $f$ and $g$ so that at ...
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A Hidato, but with a complex twist!
Today's Hidato puzzle has a pretty complex twist. What is the twist, you ask?
This is what the twist is:
There are three different colors:
Yellow: Represents a prime number
Green: Represents a ...
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0
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27 spaces, 27 curious places
Grid 1:
Grid 2:
Grid 3:
Find the meaning behind these images.
Hint 1:
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1
answer
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Shuffled binary numbers version 2
Here are 0 to 15 in binary:
0 1 10 11 100 101 110 111 1000 1001 1010 1011 1100 1101 1110 1111
I have shuffled and concatenated them to obtain the following strings:...
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2
answers
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What are the hidden digits in this long division puzzle?
The following problem was given in the Eureka journal (April 1978/University of Cambridge). This problem can be solved by hand without computers. There is a unique solution. The phrase, "exact ...
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3
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an esoteric matchbox
Seeing a vast repository of matchstick puzzles, Professor Moriarty determined to create one of his own. Behold, his greatest crime yet, the best and worst matches puzzle to ever grace this earth with ...
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2
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Shuffled binary numbers
Here are 0 to 15 in binary:
0 1 10 11 100 101 110 111 1000 1001 1010 1011 1100 1101 1110 1111
I have shuffled and concatenated them to obtain this string:
...
- 14.2k
9
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1
answer
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Fitting snakes in a cage
11 snakes are in a 6x11 rectangular cage (grid) in a zoo.
Each snake is a different length, from 1 to 11.
No snakes may overlap. No spaces are empty.
Each of the 6 rows may contain at most 2 snake ...
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2
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The Diamond of Columbus
There are up to flipping / rotation 12 distinct pentominoes.
Can you fit them without overlap in the white area?
- 56.4k
10
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4
answers
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A Prime Number equation using all nine digits once
Create an equation with the following conditions
All numbers must be one or two digit prime numbers
You can only use + and - and =
No other math operators
You must use all the nine (single) digits (...
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0
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10
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2
answers
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Shiny cryptarithm
Here's a little puzzle I made today:
$$\sqrt{\text{ILLUMINATE}^{\mathstrut}} = \text{LIGHT}$$
Most usual rules of alphametic puzzles apply here: the same letter always represents the same digit, and ...
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3
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130
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Rep Digit Palindrome expressed as a Unique set of Pan Digital Relations
Allowed Operations:
Addition, Subtraction, Multiplication, Division, Exponentiation. Right and Left Bracket use permitted.
Express $2222$ in $2$ different ways using all the digits 1 to 9 only once in ...
- 5,878
18
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3
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Playing Mastermind against an angel and the devil
This puzzle is based on a card game. There are 7 suspects and 3 of them committed a crime. The game contains 35 cards that contain the 35 possible choices of 3 out of the 7 suspects. One card is drawn ...
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2
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Last contact in custody
You came so close. The job was going so well. You just never expected that the
police would have a surveillance cat. That's what you get for trying to steal things
in an age where people are strapping ...
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3
votes
1
answer
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Justifying a redouble
This puzzle is derived from a real game of bridge I played on Bridge Base Online.
I was sitting North on board 9 (N dealer, E-W vulnerable) and the bidding turned out like this:
West
North
East
South
...
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5
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1
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Find the ciphering method 2
Link to the entire series.
The message:
3, 53, 48751, 9247757, 294914580539
The answer is a 13 letter word: UNDERSTANDING
Hint 1:
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1
answer
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Find the ciphering method using deciphered message
Link to the entire series.
Ciphered message:
...
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1
answer
152
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Techno-Culinary Brain Teaser: Unravel the Code in the Kitchen
The answer is one word.
The rebus:
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votes
13
answers
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2 vs. 1.005^200
Without using a calculator or a computer can you determine which of these two numbers is bigger: $2$ or $1.005^{200}$ ?
I saw this puzzle in a YouTube video, which I will post later.
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Find the largest number with unique digits, that is divisible by each of its digits [duplicate]
Find the largest number with unique digits, that is divisible by each of its digits.
For example 132 has unique digits and is divisible by 1, 2 and 3. But it is not the largest such number. Can you ...
- 2,694
3
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2
answers
394
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Find a Strobogrammatic number, so if we square it, the result is a pandigit number
Find a Strobogrammatic number, so that if we square it, the result is a pandigit number.
Note:
A Strobogrammatic number is a number when typed on a calculator, and the calculator is spun 180 degrees, ...
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13
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4
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77-digit number divisible by 7 with seven 7s
The smallest number divisible by 7 with seven 7s is trivially 7777777.
Then, what is the greatest 77-digit number divisible by 7 which contains seven 7s?
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5
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The distance between David and Eric
Alice (A) and Bob (B) are facing each other. They both turn $10$ degrees and now they can directly see Claire (C). If Alice turns another $10$ degrees in the same direction, she will see Eric (E). If ...
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1
answer
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Fill a 4x4 grid with minimal sum of positive integers in a way that adjacent cells contain numbers of different parity
Find a 4x4 grid containing 16 unique positive integers with minimum sum, such that adjacent numbers have different parity.
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Important Alien Message
A strange alien transcript, alongside what is believed to be a partial key, was recovered the other day. Scientists aren't sure what the message might contain, but theories point to some sort of ...
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2
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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 ...
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The Nine Gardens Of Eden
This puzzle is part of the Monthly Topic Challenge #11: Now in 3D.
There are nine distinct known three-cell Garden of Eden patterns in the Life Without Death cellular automata, including the two well-...
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1
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A take on custom ciphers
There is something hidden in the text below. Can you find out what it is? Note: no computers or tedious work required.
...
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7
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Save now! All the digits at half the price
... or double the price depending on where you're coming from
Consider the set $PD10$ of pan-digital ten-digit numbers, i.e. positive whole numbers whose decimal representation has each of the digits ...
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12
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3
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I Hate Traffic And So Do You
I need to travel through the city from my house to school, but the traffic is horrible right now.
I can only move along the city's grid with the following conditions:
• blocks with traffic (marked in ...
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1
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The minimalist game master [closed]
A game master tells his party of players that he has converted to the school of minimalism, and is going to do away with all of his dice in the campaigns they play from now on. In the place of dice, a ...
- 2,349
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0
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Puzzle "railway game set"
Alisa completes a railway game set which allows us to make various closed railway routes with crossroads. It is need to put the “rails” parts in the kit, as well as four types of “crossroads”: corner (...
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2
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What is my favorite brand of pen?
This is an entry to the Monthly Topic Challenge #3: Pencil and Paper Games
Given the following valid "tic-tac-toe" boards:
What is my favorite brand of pen?
Other possible tags to check ...
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1
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Giraffe Necked Island
Where is this island, and why is the title of this question "Giraffe Necked Island?"
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1
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A different Crack the Code puzzle
This is a different Crack the Code and get the word puzzle. Here, instead of letters, actual words are hidden.
The final word is a 7 letter famous person. That word consists of several words. I only ...
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1
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Micropoker: small hands on deck
Raise your hand if you are ready for micropoker,
which minimalistically resembles
5-card poker.
The deck has just 8 cards with 2 suits of 4 cards each.
A hand is dealt as 3 cards that are final, with ...
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vote
2
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Unravel this simple cryptic Unique NUMBER relationship
Find GC ...it is a concatenated number
Given:
N + U + M + B + E + R = GC
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1
answer
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Find the lower 8-digits number such that
This one come from newspapers in France, where this week is the "mathematics week", and some problems are proposed to kids.
This single one is easy and funny:
Find the lowest 8-digit number, ...
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10
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1
answer
299
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Equilibrium of differences
There is a subtraction equation written on the board, with three digits minus three digits, and the first digits both fixed. Alice and Bob need to fill in the remaining 4 digits (A~D below) using 4 ...
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30
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1
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PSE Advent Calendar 2021 (Day 20): Candy Cane Sudoku
This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door >
So I was ...
CommunityBot
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Numbers whose product of digits is a multiple of sum of digits
Find three consecutive numbers, greater than 10 and none with a digit 0 in it, each of which is such that the product of its digits is a multiple of the sum of its digits.
What about four or more such ...
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