The classic Orchard planting problem asks for the maximum number of 3-point straight lines attainable from a configuration of $n$ points drawn on a plane. Here we are interested in a variant of this problem. What is the maximum number of squares attainable from a configuration of 10 points drawn...

About 20% of Klondike-solitaire deals are not solvable. My question is what are the best methods to produce only solvable deals? I thought about two options: Deal a random permutation, then try to solve it with a solver, if failed, re-deal. (requires a solver like ‘Solvitaire’) Go back from the ...

Fibonacci numbers, circles, squares; everything is connected in the digital world. Can you make two squares from a circle? Seven decimals should be accurate enough. Which two numbers am I seeking?

The mood was sombre in the lawyer’s office. Eight members of the Picodie family gathered together to hear the reading of their recently deceased father’s will. Around the table sat Eli, Ron, Agnes, Tim, Toni, Eric and Levi, while their oldest sister Julia prowled around the room, peering out of...

A US state declares victory showing an important document in the last year of a wonderful 7 year period What is that?

I am unsure of the difficulty of this puzzle, but feel free to give it a try My prefix is almost dissolved My infix is an array My suffix forms nouns of action I am the key t nwl i queyh v

It's very important to keep your login details secure, which might entail not writing it down, encrypting them, or using a password manager. What you should not do is save them on some random USB and chuck it in your bag, because if you are, for example, a gang ringleader, someone might accidentl...

After a particularly rough day, Ann went to her abuela for advice. Being rather cryptic, her grandmother provided her this picture and said, "The blocks are always happy, because they remember this one thing." If you don't believe me, check out the simple markup that makes up the table! <table>

The answer to this puzzle is a list of ten thematically related words or proper names or phrases. Each of these is clued cryptically, and the theme is to be determined. Since the definition part of a cryptic clue would give away the theme, these cryptic clues use a family member (e.g., mom, siste...

A program named Lxndr.exe along with a readme.txt suddenly appeared on my desktop. The readme reads I think I show some symptoms. Do you think I suffer from it? Well, while there's definitely something wrong with my computer, I have no idea what the executable is about. Just like the sensible p...

With five I'm not from bots. With four I connect the dots. With three I seep into notes. With two I don't want jokes. With one I have three eyes. The line above is where the answer lies.

My prefix is weird. My suffix is a friend. My infix is a creature to be feared. My whole has a massive extend*. *Clarification (not needed, but may clear something up):