A stranger asks you to shuffle an ordinary deck of cards and then cut it into three heaps. He’ll bet you $20 that at least one of the topmost cards is a king, queen, or jack. Should you take the bet?

King William’s College, on the Isle of Man, has posted the 2018 edition of its General Knowledge Paper, “The World’s Most Difficult Quiz.”

“The King William’s College General Knowledge Paper (GKP) has been frustrating and intriguing a select group of quiz connoisseurs since 1904. The paper consists of 18 sets of 10 questions, each set covering a particular theme, which in many cases is far from obvious. Cracking the theme has long been one of the attractions to devotees of the GKP.”

Answers will be published on the school website at the end of January. A warning: “A Latin phrase is always printed at the top of the quiz: Scire ubi aliquid invenire possis ea demum maxima pars eruditionis est. Freely translated, this means ‘The greatest part of knowledge is knowing where to find something’. However, be warned — using Google or a similar search engine may not always deliver the expected results!”

At the same time, the Royal Statistical Society has released its annual Christmas Quiz.

“For the last quarter-century, the Royal Statistical Society has published a fiendishly difficult Christmas quiz to entertain puzzle fans over the festive break – and this year’s special 25th anniversary edition, devised by Dr Tim Paulden, is sure to get the cogs spinning after a glass or two of mulled wine. Cracking the 15 problems below will require a potent mix of general knowledge, logic, and lateral thinking – but, as usual, no specialist mathematical knowledge is needed.” The entrant or team that scores the most points wins a subscription to the society’s magazine, Significance.

(Via MetaFilter.)

These three riddles have the same answer. What is it?

He who with his hands puts it together will not be poor, and he who buys it, does not wish to use it, and he who uses it, does not know it: now you guess what it is.

— Johannes Secundus (1511-1536)

There was a man bespake a thing
Which when the owner home did bring,
He that made it did refuse it:
And he that brought it would not use it,
And he that hath it doth not know
Whether he hath it yea or no.

— Sir John Davies (1569-1626)

There was a man who bought a thing,
The thing he bought, he did not want,
The man who sold it, could not use it,
The man who used it, did not know it.

— Every Other Saturday: A Journal of Select Reading, New and Old, April 26, 1884

A problem proposed by Charles W. Trigg in the Spring 1970 issue of the Pi Mu Epsilon Journal (Volume 5, Number 4):

The digits 1-9 can be arranged in a square array so that the digits in no column, row, or long diagonal appear in order of magnitude:

Prove that, however this is done, the central digit must be odd.

From Francis Healey, A Collection of Two Hundred Chess Problems, 1866. White to mate in two moves.

University College London mathematician Matthew Scroggs has released this year’s puzzle Christmas card for Chalkdust magazine.

This year’s card contains 10 puzzles, each with a numerical answer. Splitting each answer into two strings of digits will identify two dots on the card’s cover to be connected by a straight line. Drawing 10 lines correctly will produce a Christmas-themed picture.

You can download the card as a PDF or complete it online.

A rower rows regularly on a river, from A to B and back. He’s got into the habit of rowing harder when going upstream, so that he goes twice as fast relative to the water as when rowing downstream. One day as he’s rowing upstream he passes a floating bottle. He ignores it at first but then gradually grows curious about its contents. After 20 minutes of arguing with himself he stops rowing and drifts for 15 minutes. Then he sets out after the bottle. After some time rowing downstream he changes his mind, turns around, and makes his way upstream again. But his curiosity takes hold once more, and after 10 minutes of rowing upstream he turns and goes after the bottle again. Again he grows ashamed of his childishness and turns around. But after rowing upstream for 5 minutes he can’t stand it any longer, rows downstream, and picks up the bottle 1 kilometer from the point where he’d passed it. How fast is the current?

Each day after work, Smith takes the train to the suburb where he lives, and his chauffeur meets him at the station and drives him home. One day Smith finishes work early and arrives at the suburb one hour earlier than usual. He starts walking home, and the chauffeur meets him on the road and drives him the rest of the way. This gets Smith home 10 minutes earlier than usual. How long did he walk? (Disregard the time spent in stopping and picking up Smith, and assume that the chauffeur normally arrives at the station just as the train does.)

By Eugene Woodard. White to mate in two moves.