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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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 ...
8k views

First digit of 3^2020

Inspired by The last digit for 3^(2019) Can you find the first digit of 32020 without a computer?
126 views

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 ...
81 views

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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 ...
2k views

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 ...
830 views

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 ...
243 views

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 ...
371 views

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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Find the ciphering method using deciphered message

Link to the entire series. Ciphered message: ...
152 views

Techno-Culinary Brain Teaser: Unravel the Code in the Kitchen

The answer is one word. The rebus:
8k views

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 ...
394 views

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, ...
2k views

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?
906 views

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 ...
116 views

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.
1k views

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 ...
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 ...
303 views

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-...
1 vote
265 views

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. ...
1k views

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 ...
4k views

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 ...
250 views

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 ...
153 views

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 (...
2k views

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 ...
190 views

Giraffe Necked Island

Where is this island, and why is the title of this question "Giraffe Necked Island?"
309 views

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 ...
357 views

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 ...
1 vote
179 views

Unravel this simple cryptic Unique NUMBER relationship

Find GC ...it is a concatenated number Given: N + U + M + B + E + R = GC
713 views

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, ...
299 views

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 ...