# 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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### 1 0 1 0 1 0 1 0 1 0 1

Start with the digits:       $1\ 0\ 1\ 0\ 1\ 0\ 1\ 0\ 1\ 0\ 1$ You may then add (only!) these simple arithmetic operators:       $+\ -\ \times\ \div$ You may also ...
226 views

### Does he like them or not? Another Grandpa Mystery

Now I know very well the weird likes and dislikes of Grandpa. Yesterday he tells me: "Son I like Queen but not the Queen I liked the King but not the King I like Monarch but not ...
955 views

### What was my friend doing?

I asked my friend what he did last week and he gave me this note. ivoesfe ivoesfe ivoesfe hppe nfo hppe nfo uif tjohjoh sbjo pof gmfxdvdlppt oftu qbbnfsjdbosjt nvujozcpvouz ...
198 views

### Holy Alphabet Arithmetic

$Given$: $A$+$B$+$C$=3 $B$+$C$+$D$=3 $C$+$D$+$E$=1 $D$+$E$+$F$=1 What is $E$+$F$+$G$=?
162 views

### Devil in Different Disguises but in Prime Shape…Can you Figure out his Diverse Expressions?

$Given$ $Devil$ goes by $666$ Express him as 1). Sum of all Primes in 3 Different ways using all the digits 0 to 9. Use only + sign. 2). Sum of all Squares of Primes. Use only + and ^ signs. 3)...
129 views

### Cube the digits and carry on

Take a number between 2001 and 2100 inclusive. Cube the digits of the number and add them together, then repeat the process with the new sum and restart the process over and over. For example if I ...
165 views

### Polygon neighbors

This question is from the German mathematics competition Känguru der Mathematik. In this competition students have to solve 30 mathematical tasks like this in 90 minutes without calculator. Actually ...
264 views

### Fibonacci progression

In a number sequence, 1, 13, 169 and 2014 are respectively the first four terms of the sequence. The next terms are equal to the sum of the four numbers that precede them. For example, the fifth term ...
223 views

### Minesweeper puzzle - Too many twos

A Gobo is caught for leaving the school for the lnternet bar to play computer games without permission. He is asked to solve a problem. Put 4 mines in a 3 by 5 minesweeper grid to fill ALL the other ...
334 views

### What was Grandpa really doing?

"Guess what happened during my walk". Said Grandpa "I saw gods in a ghetto"! He continued with a smile. "What?" I said. "Well, not really. But can you guess what I did?", Grandpa asked. ...
660 views

### Pan Digital Lucky Seven wants you to figure out all the digits

$Given$: A, B, C, D, P, Q, R, S, T are distinct digits varying from 1 to 9. AB, CD, PQ, RST are all concatenated Numbers. From the given expression , figure out all the digits to make lucky seven. ...
242 views

### Happy New Year?

Extend this infinite series by five more terms: 17, 3, 5, 7, 11, 17, 2, 3, 5, 11, 13, 17, 2, 5, 7, 11, 13, 2
255 views

### A Criminal Conspiracy (Who is guilty #5)

[This is continuing from previous puzzles. #4 was quite tricky. This one is meant to be much easier (I'm testing the boundaries here). I've been testing various versions and would love your thoughts. ...
177 views

### A Simple Math Puzzle

So my last math puzzle was too easy apparently, and this one might be too. Either way, the rules are the same. No rotation. No duplication. No combination. No rounding. No computers. Good luck to ...
4k views

### Strategy for 2x3 Sliding Puzzle

Here's an instance of a $2$x$3$ sliding puzzle: The $2$x$3$ sliding puzzle is just a smaller version of the well-known 15 puzzle. Many guides exist on solving the 15 puzzle, and there are strategies ...
262 views

### PFG: A pretty spiral!

PFG = Paper Folding Golf You bought a piece of paper from your local op shop, but your shop is always dodgy. So instead of a normal piece of A4, you got an infinitely long strip, a metre wide. (...
206 views

### Honeycomb structure statements (T/F)

2 1 1 3 0 2 1 Above honeycomb structure contains numbers. A number at each cell represent a statement. x : This cell is surrounded by x True statements. ...
178 views

### An alphametic for Nikolai Gogol

"Diary of a Madman" (Russian: Записки сумасшедшего, Zapiski sumasshedshevo) is a short story by Nikolai Gogol. MAD * MAN = ASYLUM Which digit does each ...
92 views

### Follow the path of relation through the grid #8

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
97 views

### Follow the path of relation through the grid #4

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
166 views

### Tiling rectangles with Hexomino plus rectangle #3

Inspired by Polyomino T hexomino and rectangle packing into rectangle See also series Tiling rectangles with F pentomino plus rectangles and Tiling rectangles with Hexomino plus rectangle #1 ...
126 views

### Hand tiling puzzle 2

Here's another set of polyominoes (sizes 4,5,6,7,8,9,10) that you can print and cut out. As before, the two smallest (same pieces as previous version) make a 3x3. The rest of the pieces are different. ...
422 views

### A Puzzle about “Codeforces Subsequences”

I'm quite intrigued by an "easy" problem in recent Codeforces contest: Codeforces Subsequences. In this problem, you have to create a string $T$ as shortest as possible such that $S =$ &...
76 views

### Multiples of their reversals

8712 and 9801 are the only 4-digit numbers which are multiples of their reversals: 8712 = 4*2178 and 9801 = 9*1089. Without using a calculator/computer, can you find two 5-digit numbers with this ...
188 views

### Rotary phone with numbers and letters

I am going to organise a quest for teenagers. I have a vintage phone like below: I am looking for ideas how to use the rotary phone with numbers 1,2, ..., 9, 0 and letters A, B, C, F, H, I, K, L, M, ...
187 views

### Back in time, in my time, all the time

I present to you all a highly interesting problem that I came across awhile ago on Tim Krabbe’s site. It’s White move and win, i.e. reach a winning positon, in 21 moves. David Gurgenidze & ...
120 views

### A condemning alphametic

Every question mark and every letter stands for a base-10 digit Different letters stand for different digits Question marks are placeholders and stand for arbitrary digits (such digits also may occur ...
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 ...
125 views

### Fill in numbers on the cube … again!

You are given a cube. You are told to fill in each face randomly with some of the numbers $4, 5, 6, ..., 11$, with no repetition. What is the probability that for each two faces that are connected by ...
111 views

### Alphametic puzzle, involving square and prime numbers [closed]

I have been trying puzzle solving recently and came across this problem. Any hints on how to do this? So far, I have found that N, R and F must be odd (as they are the last digit in a 5 digit prime ...
186 views

### Valiant Knight is back..but he is in grave danger from the Evil Queen

King has placed a bounty on Valiant Knight and enlisted his evil queen’s help. Queen knows knight’s regular stops of his journey and knows he goes through all odd prime cells. She strategically ...
111 views

### Take out one Third..Keep Two Third..To Total Ten

There are total 36 numbers in the grid shown in the picture. Cross out 12 of them and keep 24 of them. Sum of the rest of the numbers should total 10 for each row and column.
170 views

### Normal Knight sees the Big Picture during his Countrywide Travels [duplicate]

Normal Knight is savvy, energy saving as he travels through Regular Country... Ride along and Document Details of his Journey As this Knight (only chess move allowed) journeys through , he takes ...
115 views

### A Lollipop with Roots

$Given$: $S$, $T$, $U$, $V$. are distinct digits which can vary from zero to nine, with $V>U$. $ST$, $STT$ are concatenated Numbers. Deduce S, T, U, V from the following relationship. ST=\...
604 views

### The SUM 50 Game

Attached Grid (Total 5 x 5) has a black box grid (3 x 3) inside it. The Black box grid needs to be filled out with numbers 1 thru 9 using all numbers once. The Outer Red box squares (Total 16 ) need ...
281 views

### Find a Strobogrammatic number, so if we square it, the result is a pandigit number

Find a Strobogrammatic number, so 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, ...
146 views

### Anakin, Obi-Wan and Dooku are a match for Sidious!

Darth Sidious is too powerful. Anakin and Obi-Wan discusses and convinces Count Dooku (Darth Tyrannus) to fight against his own master. It is the only way they can be a true match against the Dark ...
99 views

### Find the unique passcode

"Is this the Coldport Lost Property Office? I think I left my puzzle-book on the train this morning, and I was hoping someone had handed it in." The speaker was a tall gentleman with a six-...
127 views

### A Breeze Through

Here's a small problem for you all to breeze through tonight! It's White to move and selfmate themselves in 7 turns. Can you tell me what the special concept is that arises from this problem? As ...
120 views

### Dissect a square into 1:2 non-congruent integer-sided rectangles

(Similar to the recent 3:1 and my 3:2 rectangle question) Tile a square completely with rectangles which have aspect ratio 1:2, integral side lengths and all different sizes. In other words selected ...
298 views

### KenKen Zen: The Cluelessening

As our KenKen voyage of cluelessening­* began, some clues remained entirely hidden from us.  Though much remains to be discovered, we may now be entrusted with all clue amounts at once.&...
306 views

### The Multiple Choice Test Test

One day, the logic professor announces a pop quiz. "All questions in this test are about the test itself. In fact, the test is open note since you have a copy of the test itself. Good luck!" 1. What ...
420 views

### Grandpa's Numbers

Grandpa likes pencils but not pens Grandpa likes Beijing but not Tokyo Grandpa likes math but not chemistry Grandpa likes Contact but not _______ Make sure to explain! Hint 1: Hint 2: Hint 3:
1k views

### Fill in the 3 letter blanks

Please fill in the 3 letter blanks in the following numbered list 1 --- 2 CAD 3 --- 4 CNY 5 --- 6 AUD 7 --- 8 ARS 9 --- 10 --- Please no computers/internet. A complete list would ...
629 views

### Grid Puzzle - Paint

A student was found making Graffiti in the teacher's office. He was punished and was asked to repaint the wall of the room. The teacher gave him a grid to show which part of the wall should be painted ...
189 views

### Cathy’s Composite party is powered by three Prime Pals. Can you find them?

Given: A, B, C are 3 distinct primes. Find the smallest composite number Y that satisfies the relation: $Y = A ^ C + B ^ B + C ^ A$
581 views

### Multiply 2 palindromic alphametics to make a pandigital number

There are some different definitions of pandigital numbers, so to avoid misinterpretation, lets use this definition: Pandigital numbers (pandigit) are numbers containing the digits 0-9, where each ...
748 views

### Move 2 or 3 spaces in this 5 by 5 grid

You have a 5 by 5 Board as shown. You start from the S (Center) position. You can: 1 Move TWO or THREE spaces only 2 You can move Vertically or Horizontally or Diagonally but only in a straight ...