Top new questions this week:

Pipes Puzzle Uniqueness

In the puzzle game Pipes, a space-filling tree of pipes (which may have either one, two, or three neighboring connections each, but not four) is scrambled by a series of tile rotations, and the goal ...

logical-deduction grid-deduction

Middle-Aged Life

I've always been fascinated Conway's Game of Life, but one thing that always bugged me was the idea that a cell could live forever. There are alternate rulesets (e.g., Generations) which address the ...

cellular-automata

Folding a piece of paper with numbers in sequence

Divide a rectangular sheet of paper with a side length of 2 × 4 into eight 1 x 1 unit squares and label them as shown in the sketch. Then fold the sheet of paper along the boundaries of the square so ...

mathematics geometry paper-folding

Deriving a 3x3 grid from another one

A $3 \times 3$ grid $G$ is filled with every number from $1$ to $9$. Now a new $3 \times 3$ grid $H$ is formed, such that $H_{ij}$ is the number of neighbors of $G_{ij}$ that are greater than $G_{ij}$....

mathematics logical-deduction combinatorics no-computers grid-deduction

Sudoku: Episode 64 - Attack of the Clones

An 8x8 Sudoku where you technically only have to figure out 32 cells! Twice Half the cells, double the clues! Penpa Link Rules Normal Sudoku rules apply. Values are 1-8. Boxes are the 4x2 regions ...

logical-deduction grid-deduction sudoku

Communists and Christians

Across 1. Singer Collins is performing leads for Prince (6) 5. Broken spine leads to aches (5) 10. Say, 33 across and Cuiabá's northern tip, described by excellent lyric poems (9) 11. Predecessor to ...

cryptic-crosswords

A Connect Wall You Can Count On

The 16 words below may be partitioned into 4 groups of 4 connected words. The resulting four words also have a connection which is a seven-letter word. ONE POTATO PINK FOUR CORN RANCH SOY SINGLE ...

word knowledge pattern connect-wall

Greatest hits from previous weeks:

I am a computer’s nightmare, but a programmer’s best friend

I am a computer’s nightmare, but a programmer’s best friend. I am both the cause of a problem and the source of its resolution. What am I?

riddle

I am a seven letter word- who am I?

I am a Seven Letter word. I like Mornings If you remove my first letter you can drink me. If you remove my first and second letters, you may not like me If you remove my last letter, you will see me ...

riddle

Swap the edges in a solved Rubik's cube

I have a rubik cube, which always have two swapped edges in the last layer. No matter which color I start with, there are always two edges in the last layer which remained swapped with each other. ...

rubiks-cube

Make numbers 1 - 32 using the digits 2, 0, 1, 7

This is similar to the "Four fours" puzzle, but using the digits 2, 0, 1 and 7. Rules: Use all four digits exactly once Allowed operations: +, -, x, ÷, ! (factorial), exponentiation, square root ...

mathematics formation-of-numbers

29 - 1 = 30 how?

How is 29 - 1 = 30? If also 14 - 1 = 15 11 - 1 = 10 9 - 1 =10. Hint:

lateral-thinking

What is the largest tile possible in 2048?

I can get to 4096 max. There are videos on youtube of guys making it to 8192. What is the theoretical maximum limit on this? PS: if you haven't played this, here is the link to addiction.

game 2048-game

IQ test puzzles - diagonal line shapes, curly line shapes

What is correct answer for these two IQ puzzles and why?

pattern progressive-matrix

Message passed between friends in a library

Mary met her friend Jenny in the library. They gossiped about various things and then each chose a book and went to separate corners of the library and sat down to read. After half an hour Jenny went ...

cipher

I previously created a combined slitherlink and sukoku puzzle, but I was unsatisfied because the grid was smaller then a regular sudoku. So I made another, larger one. Below is a 9 by 9 grid. This is ...