h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I found a link on a page I was looking at to the Puzzle for today. Never knew it existed.

Anyway, yesterday's puzzle

http://www.bbc.co.uk/programmes/articles/2vFydR4vmLj9djZnY64WsBt/puzzle-for-today

Reads as follows :

Puzzle No. 557 – Friday 30 August


Four houses next to each other have numbers which add up to 50. What are their numbers?

Today’s #PuzzleForToday has been set by David Feather a retired maths education lecturer



Click here for the answer









So I tried to work it out, but 9+11+13+15=48
10+12+14+16=52




Then I checked the answer to see how they did it.



It said:





17, 19, 21, 23

That is fascinating...

Looks like 8 was misread as 5 when the question was typed up, but it shouldn't have been that hard to check the answer made sense before it was put online

The BBC probably is not going to stand or fall based on one mistake. Even a major mistake could be survived if they begged for forgiveness.

Heh... Puzzle fans can be vicious when they feel slighted.


I read/heard a story about a major jigsaw puzzle maker in North America who had a "puzzle of the month" promotion. These were high quality and challenging puzzles. One year they thought they'd be a bit cheeky with there rabid fans for the month of April. As an April Fools joke, they sent out a puzzle missing one piece.

Their fans did NOT have the sense of humor they anticipated. They were FURIOUS. In response, the company sent to all their subscribers not only the missing piece, but a bonus, (complete!) puzzle.




I don't consider jigsaw puzzles to be proper puzzles. They're solved by nothing other than trial and error. I believe jigsaw puzzles aren't meant to relieve boredom but to enhance it. And yes, I consider Pentominoes, which I wrote about here years ago ( A970904 ), to be essentially a jigsaw puzzle.

its a puzzlement.

(I will skip a link to the Yul Brynner song .)

"Puzzle fans can be vicious when they feel slighted. "

Yes - the Twitter thread about the #PuzzleForToday was impressive!

I see the 30 August puzzle has been updated, and didn't just change 50 to 80 - they have redone the question and the answer

Jigsaws aren't quite trial and error, as there are a few clues you can use to find the relevant pieces, but I agree they're not proper puzzles and I don't find them particularly satisfying these days... Great Entry about Pentominoes - very clear

I'm thinking back over the years. Did I ever trust the BBC, or did it just seem dull?

(Except for H2g2)

I thought they might correct it at some point, which is why I copied it. I should have taken a screen shot I suppose, but how pedantic do we want to be?

I've never looked at Twitter, but I expected I wasn't the only person who had noticed this. Did the chappy who devised the puzzle (David Feather) throw in his ?

I would still class Jigsaw puzzles as puzzles as you can use strategies to 'solve' them in the same way as most puzzles need a certain method.

Some puzzles are easier & faster to do than others. I enjoy crossword puzzles but generally can't be bothered with number ones.

Here is the Twitter thread http://twitter.com/BBCr4today/status/1167322828791640065

Looks like David Feather didn't comment, but people noticed the problem, and that it had been updated People found a few alternative answers in there

"I enjoy crossword puzzles but generally can't be bothered with number ones."

Yes, same for me - I don't have a set of properties of numbers at my fingertips like I do with words and their letters, so I find 'crossnumbers' much harder and more time-consuming to complete...

Meh, the main strategy to use with jigsaw puzzles is trial and error.

I suspect my opinion on puzzles is similar to my opinion on what should qualify as Olympic "sports": My opinion in which I know I'm right but has no effect on reality or popular agreement.

My preferred style of puzzles range from topographic puzzles like the sort of ring and chain puzzles you might find in a pub, to Sudoku and crosswords. I also like a good logic puzzle. Here's one of my favorites.

Given: On Friday morning a hiker starts from the base of a mountain trail at 7:00 am and begins hiking up the mountain. He remains on the trail but he varies speed and takes some number of rest breaks along the way, and arrives at the mountain peak at 5:00 PM. He camps overnight and begins his trek down the mountain at precisely 7:00 am again. It takes less time to go down the mountain, again varying his speed and stopping at random spots along the trail on the way down, and arrives at 3:00 Saturday afternoon.

Your goal: Prove to me that there will be a spot along that trail where the hiker would have been at the same time of day both Friday and Saturday. N.B. You do NOT have to tell me where that location is. I can't stress this enough.










(If I were King of Everything, there would be no "sprots" requiring judges. That means no gymnastics, synchronized swimming, diving, &c. Also no boxing, karate, fencing, &c unless they are decided by submission or KO. Sprots should be decided by speed, time, distance, or points scored. I want only definitive winners. You can have referees to prevent cheating and foul play, but no judges. N.B. I am NOT saying things like gymnastics and synchronized swimming aren't athletic, they certainly are, but so is Professional "Wrassling".)

You don't strictly *need* judges in boxing or other combat sports. But the alternative is a last-man-standing wins scenario. I'm suspecting the limited Time and hence judging thing, came from wanting to minimise the death-count in those

I'm glad you're not King of Everything. . If I was king of everything - each to their own - would be a strong driving philosophy

Being King of Everything would be too much work, BG. Some kings get exhausted from resolving disputes right and left. This ultimately drives some of them to depsotism.

For what it's worth, I think that some sprots exist because they get high ratings on TV. Figure skating is very pouplar. Take away what viewers actually want to watch, and fewer events would be televised.

Yep... don't care.

My stance on the Olympics is that since they are purportedly about bringing together nations for fair competition, judges just get in the way of that goal. There are constantly accusations of bias and even cheating amongst judges. (I'm looking at you France with your figure skating judge in 2002.) I want only objective competition.

Also, I would end this endless competition amongst cities vying to be hosts of upcoming games. I'd end that and decree that Greece will host the Summer games and Switzerland host the winter games hence forward, DONE!

I'd fix the crappy television coverage (US) while I'm at it. One of the big problems with the Olympics is how they only show the popular sports. It's about ratings only. No more official network monopolies on the games. I'd still let some network pay to be the "official" one, but they'd only get first option, any events they don't cover, any other network is free to air them. And every event should be available live for streaming or download. My father loves archery and they never cover archery other than in a quick recap of all the other things you missed while they have 4 channels of gymnastics running.


I'd be the very model of a modern major despot. But I'd only use my power for things I choose. Any other issues is up to you to resolve on your own. It's no fun being king of everything if you have to actually be king of EVERYTHING!

In theory I see a lot to like in your proposal. In practice, I see human nature as being the main deterrent to making it come to pass.

I don't watch the Olympics much anyway. "I, Tonya" and "Eddie the Eagle" are as close as I come to paying much attention to them.

Greece for the summer games and Switzerland for the winter ones are perfect solutions. Too perfect. Perfection has not worked for us since before the Garden of Eden.

I think I see what you mean, BG - figure skating competitions could take place, but they wouldn't be classed as sport. Those were the days when painting was an Olympic sport

Anyway, to the puzzle... I'm not sure I can prove it, but if I were to attempt to prove it, I would be saying something along the lines of:

The journey up the mountain is some sort of continuous function of time f(t), and the journey down the mountain is another continuous function g(t). f(t) has gradient greater than or equal to 0 at each point while g(t) has gradient less than or equal to 0. g(7am) = h, where h is the height of the peak, while f(7am) = 0, and f(5pm) = h while g(3pm) = 0. Drawing a graph of the functions, they are constrained inside the rectangle [7am-5pm, 0-h]. If the curves did not intersect at some point within the rectangle, then they would have to be parallel lines, but either they intersect at h=0 or h>0 and there must be at least one point on each curve with non-zero gradient so they are not parallel lines and hence there is a point on the upward and downward journeys where the hiker would have been in the same place at the same time of day.

I'll accept it. I know of two general ways to prove it, and this falls under what I think of as the "graphical" method. Once you understand the situation, it's obvious that there HAS to be some point. The problem is finding a way to express that understanding.

One fellow gave me an "Audio/Video" method. He proposed that the hiker record his trip and the footage be reviewed afterwards to determine the exact spot. I gave him a half point (out of 10) as his method would, indeed, work, but as I stated, I don't care where that location is. He was, again as so many people I've posed this to have done, trying to provide me with the exact location.

I was also thinking along the graphical representation path. Since that has already been given, I will try to come up with the non - graphical one. Please continue living while I ponder this, it could take a while to formulate.

The displacement in time on both days can be described by integrating the two random speed functions, where speed lies in the range of positive to negative infinite, but the displacement is constrained by 0 to h going up and 0 to -h going down.

In order to avoid being in the same place at the same time, the sum of both displacement functions must never be equal to or bigger than zero.

At t=15:00 on the second day the hiker reaches height 0, which is the lower constraint of the upward journey, leading to a sum of 0 or higher, thus proving that the point of equal time / place must have happened at 15:00 latest.