All Questions

Take the first 10 primes. Can you divide them into $g$ disjoint groups, such that the sum of numbers in each group is prime. In particular can you make this work for every value of $g$ in the range $[...

From me you can borrow, but only for a while. You've got to give it back or you'll pay a debt. I won't borrow from you, that's not my style. But you can give to me and some money you'll get. I'm ...

An entry in Fortnightly Topic Challenge #48: Unusual tag mix After solving the following cryptic clues, find the following properties: A major property that all ten words share. A minor property ...

Complete the image below with the correct strings of letters in the correct squares (four squares will be left empty). Transcription (■ is a square that does not exist in the image, and ? is a blank ...

A pure checkmate is a checkmate where for each square the king might go to, there’s exactly one reason it can’t. The famous Légal mate is one example, so is a KR vs K checkmate. What’s the minimum ...

A [prefix] at [infix] early [suffix] can't [whole] everything. What is the logical statement when the gaps are filled?

What letter comes next in the sequence: A, P, I, W, A, T, ?

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the final puzzle in this series! For more information about the series, see the first ...

This is a Curfew variant. Curfew is a genre invented by Hempuli; I made a slight modification to give this variant. Rules of Unequal Curfew: Draw a loop that visits every circle. Each visit to a room ...

Mirror mirror in the board Decipher the riddle of this horde How many moves to it, please? To put my brain at ease! Both sides help, follow their paths The solution you must craft Oh, and there is but ...

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" The grid below is a normal Sudoku grid with normal Sudoku clues, but the completed grid also houses a Statue Park! The completed ...

Why is 'logjam' the answer to 'function held up by traffic blockage'? I guess 'log' is function, and logjam is blockage but why 'jam/maj'? L,G & A are all correct.

An entry in Fortnightly Topic Challenge #47: Wacky Sudokus. Edit: Clarified three of the rules. Rules: Normal sudoku rules apply. Inside the sudoku, there exists one "loop". The loop ...

What is the trick to constructing a heptagon and a nonagon which have all their sides equal? The length of the side has to be a natural number. Your answer should include a drawing of the two polygons....

I have been trying to write a program (just for fun) to solve Einstein’s Riddle, see https://play.google.com/store/apps/details?id=com.rottzgames.logic. My solution basically does this: It creates an ...

Given the following shape - an hexagon ABCDEF of which a parallelogram CDGH is cut out. With a single cut divide the shape into two equal area shapes by means of an unmarked . You may draw lines and ...

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the penultimate puzzle in this series! For more information about the series, see the ...

Which of the three options fit in the central Octagon which is common to the two diagonals, one vertical and one horizontal row? Separately, each diagonal row (Brown and Red boxes), the horizontal row ...

In the film Tomb Raider (2018) there is a wooden puzzle-box with rotating sections. Once the correct sequence of moves is performed, a drawer pops out. See here: Upon seeing it she says: Karakuri. ...

Paint the cells of a 5x5 grid with 𝑛 colors, such that every possible tetromino found in the grid uses 4 different colors. What is the smallest value of 𝑛 possible in such a coloring? Here is a ...

Paint the cells of a 4x4 grid with 𝑛 colors, such that every possible tromino found in the grid uses 3 different colors. What is the smallest value of 𝑛 possible in such a coloring?

J.R.R. wrote about the dragon, thinking of these men. Issur performed and challenged the locals to do a crossing, thinking of these men. G.R.R. wrote about the killer of the giant, thinking of these ...

What is the largest number, which can built as a sequence (from left to right) of different two-digit primes only? For example, 1371731 is valid, 137131 is invalid (containing 13 twice), 139717 is ...

I can't figure this one out. Any help would be appreciated. Journalist-in-training Janet Seymour's byline appeared in the Carson City Chronicle on six days last week. On each day (Monday through ...

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the twelfth puzzle in this series! For more information about the series, see the first ...

Eight clues are thematic and are clued by word-play only. Each of these eight clues' word-play has an extra letter which is not part of the answer. These letters cryptically indicate something, ...

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" This puzzle consists of three overlapping Sudokus, coloured red, blue and green, so each cell will contain three digits, one of ...

I saw this puzzle on Twitter by user @lilva_0419 and I personally feel that it is impossible to solve. Can you prove me wrong (or right)? Source on Twitter Try it online Rules (see Wikipedia): ...

I saw this on a forum and no one knows how to solve it, and it's driving me crazy. Does anyone know what the solution is and why? I tried looking at similarities in the columns, rows, and diagonals. I ...

There are 5 boxes labeled A, B, C, D and E. Each box contains a distinct number, but you don't know what it is. You can select three boxes and the Oracle will tell you which box contains the median* ...

Let's have a 10x10 grid. We want to create a Sudoku in which, in each row, the pairs (a+b), (c+d), (e+f), (g+h), (i+j) add to one of the following numbers: 7, 9, 11, 13, or 15. Can you construct a ...

Fill in the numbers 1 through 9 in the 9 empty cells (each number appears exactly once) to make the row and column expressions equal to the number at the end of the row or column. Regular math ...

I received a bag of wooden pieces, but cannot figure out what the puzzle is supposed to be. I've tried several burr options and several Alketruse puzzles, but cannot find the correct configuration. ...

All sides of a triangle T1 are shorter than the shortest side of a triangle T2. Is it always possible to put triangle T1 completely inside triangle T2?

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to the eleventh puzzle in this series! For more information about the series, see the first ...

If I have a multiple choice question where $\int_ {e} ^ {2e} \frac {x} {\ln(x)} dx $ is equal to: a) 6.55... b) 7.28... c) 7.93... d) 7.96... e) 8.10... f) 10.10... the ... means that there is ...

Gaby numbers her 21 students with the primes between 11 and 97. She now asks them to sit around a circle making sure that any two of them sitting next to each other have either their tens or units ...

My friend said to me: “In February of the year 1970 at 1:12 AM Ma turned 18. Ma turned 34 in February of the year 2002 at 2:16 AM. How is this possible?” “And yes. Same Ma!” he ended with that. Hint ...

I am posting an interesting problem which I find in my local magazine named 'Dainik Bhaskar' in the riddles section. At first sight, I think this will be an easy one. But I am wrong. Can anyone help ...

Since it's the 20th of January, perhaps we can demonstrate an orderly transition from TRUMP to BIDEN? There are eight steps to get there and all words are found in the World Scrabble dictionary. One ...

Here are 6 places I visited in 2008: Now tell me, where was the Sun?

The puzzle is as follows: The figure from below shows a lock mechanism used to store sensitive data microfilms from a certain lab. This mechanism is magnetic and consists in numbered buttons which ...

The puzzle is as follows: A dairy plant in Milwaukee is well known for its yoghurt. However during the quality control a factory worker forgot to bring a set of adequate vessels to measure the ...

What do these three towns have in common? "Dublin", "Blackpool", "Chernobyl".

You are given 3 containers - pictured in this order below: a box with side 2, height 1, and a cone with base radius 1 and height 1 in the middle. a box with side 2, height 1, and a half sphere with ...

I got [prefix] [suffix] [infix] from washing the [whole]. P.S. I [infix] the [whole]. The note above, when the gaps are filled, will be a grammatical and reasonable note. What is the note?

The puzzle is as follows: (Transcription with grammar errors fixed) A game consists of the following: The challenge is to flip the chips in such a way so that they are as in state 2. You start in ...

Fill in the nine X spots in the following equation using each of 1, 2, ..., 9 exactly once, so that the equation is satisfied. The XX in the denominator denotes concatenation of two digits. $$ \frac{X}...

In the sea or in the sky Sometimes also in your eye. Melancholy feels like me But energy I have plenty. Into me you have vanished Out of me you're astonished What am I?

So this challenge is you have (don't have to) make the numbers 1 - 100 by using the numbers 1, 3, 4, 6 only once. I'm stuck on how to make 54. Can anyone help me? P. S. You can use +, -, ÷, x, ! And ...