The answer to this puzzle is 18. What could be the question that led to this answer?

Uncle Nestor is a renowned global traveller, and can never stay focused on the one thing for too long. In an attempt to pass the time through the current global travel restrictions, Nestor thought it would be a great idea to construct a crossword of all the countries he's visited. The trouble wit...

A Golomb ruler of order $n$ is a straight line with $n$ marks such that no two pairs of marks are the same distance apart. We can extend the concept to circles. Place $n$ marks on a circle such that no two pairs of marks are the same distance apart going clockwise or counter-clockwise. I will ca...

I am unable to finish this Sudoku. All numbers are verified by the app. I'm sure there must be a way to solve this without guessing. Even an online tool couldn't tell me a next number.

In the spirit of the What is a Word™/Phrase™ series started by JLee, a special brand of Phrase™ and Word™ puzzles. If a phrase conforms to a special rule, I call it a Computer Phrase™. Use the examples below to find the rule. $ \begin{gather*} % set Title text. (spaces around the text ARE im...

Things were quite different in 3000 AD. We'd discovered other planets with sentient life for instance. Five to be precise. Adam, Bill, Carl, Dave, and Eric we called them, and we used the lately discovered instantaneon beams to communicate without delay across the vast distances between us. Light...

my school is hosting a crypting hunt, and here's a puzzle I can't solve even after 4 hours. Please help me. There is no question, just 2 links given: https://hstatic.halocrypt.com/begin.txt http://ihasabucket.com/ There is also a hint: Perhaps basic maths could help. Please help me solve th...

Let $k$ be a positive integer. Amy and Ben are playing a game, with the number $1$ written on the whiteboard initially. Amy and Ben do the following in order, starting with Amy: Suppose the number on the whiteboard is $n$. The person who is making the turn chooses $d$ which is a divisor o...

The Liar, the Random and Truth teller were captured and brainwashed to forget whether they always lie or tell truth or randomly answer.Everyone is handcuffed to a chair and gagged with gray,white and black handkerchief. Each one was given a phone with apps to guess who among them is the right Lia...

Number sequence questions are normally not received well here but I thought this one might warrant a bit more attention as it has the following interesting properties: It is a finite sequence. Each element of the sequence appears exactly once. It does not appear on OEIS but is clos...

In a plane, there is a robotic arm consisting of $n \ge 2$ segments of length 1, like this: The first segment is fastened to a single point ("origin"), but it can rotate freely around that point. All other segments are connected to the previous segment by means of a joint, so they can bend with...