Two great Martin Gardner puzzles this week….
1) Can you change 100 into CAT by moving just two of these matchsticks?
2) Can you draw one line (it needn’t be straight) that will divide this figure into two identical parts?
As ever, please do NOT post your answers, do say if you have solved them and how long it took. Solutions on Monday.
Update: Here is a ‘personal’ magic square that I created as part of the Martin Gardner Mind Party in Edinburgh…
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October 22, 2010 at 5:40 am |
Two minutes for solutions to both, but you never know with Gardner
October 22, 2010 at 5:49 am |
Got the first puzzle almost immediately. I’m still trying to figure out the second.
October 22, 2010 at 5:54 am |
I definitely managed the green shape, and think I have the matchstick one. About 2 mins total.
October 22, 2010 at 6:04 am |
2 minutes for both.
first one as I was reading the instructions, second had to draw on paper, then it became obvious.
October 22, 2010 at 6:05 am |
I’m with Allison. First puzzle; Yup. Second puzzle; Not sure. Although it may be dawning on me now…..
October 22, 2010 at 6:06 am |
Nope. Still nothing on the second >:O(
October 22, 2010 at 6:09 am |
I have a solution for the second puzzle. It helped to use squares.
I am not convinced about the first puzzle, but I have a weak solution.
about 30 seconds for both
October 22, 2010 at 10:06 am
Ha! Don’t be put off by a weak solution, a lot of Richard’s are pretty weak too.
October 22, 2010 at 6:13 am |
Good Morning Richard, I solved the CAT puzzle but this was only because Ive seen this before, that being said, im still working on the 2nd shape.
October 22, 2010 at 6:16 am |
About five mins each, but whereas my solution for the second is perfect, for the first I had to … um …. apply some artistic license to one of the letters.
October 22, 2010 at 6:57 am
I’ve got a better solution for the first one now.
October 22, 2010 at 6:27 am |
Got the 2nd one and I think I see 2 solutions to the 1st one.
October 22, 2010 at 6:58 am |
5 minutes. Got the second much quicker than the first!
October 22, 2010 at 7:00 am |
Like almost everyone, I got the first one straight away. However, the genius lies in getting the second one…. and I am stumped. Sadly not a genius then.
October 22, 2010 at 7:11 am |
Got the first after a couple of minutes. I was about to give up on the second when a solution suddenly presented itself. I guess my unconscious is better at maths than my conscious mind.
October 22, 2010 at 7:14 am |
Couple of seconds each
October 22, 2010 at 7:17 am |
puzzule No. 1: 5 seconds
puzzule No. 2: …..give me a few days
October 22, 2010 at 7:17 am |
sorry puzzle no puzzule
October 22, 2010 at 7:29 am |
15 seconds for the first, 30 for the second (mostly drawing it out again).
October 22, 2010 at 7:37 am |
First – about 10sec
Second – only after mathematically analyzing possible types of shapes – 3 mins.
But maybe my mind has been working in the nicht, since following all links related to the G4G events, i stumbled on the link to the three visual treats
http://www.g4g-com.org/storage/resources/CoM-Three_Visual_Treats.pdf
but did not spend any substantial time to solve it, only digested the info.
But since the human mind still has many unknown ways of working, i assume some part of mine has been working on it.
October 22, 2010 at 7:46 am |
Jepp, (few seconds) and Jepp (few seconds)
October 22, 2010 at 7:47 am |
Holy cow. Actually got a solution for each in under 5 minutes. About time as I normally struggle for hours… good stuff.
October 22, 2010 at 7:57 am |
lol just did the cat one lol took 3 minutes a great trick, now for the other one
October 22, 2010 at 7:59 am |
Nice enough. first one took a few mins, second one was almost instant.
October 22, 2010 at 8:01 am |
1 minute for 2nd pic not bad for a 98 Iq level
October 22, 2010 at 8:18 am |
Both in a few seconds – don’t think I’ve ever been able to say that before – must just be lucky that these ones are suited to my brain.
October 22, 2010 at 8:20 am |
1) Yes.
2) Yes.
50 seconds
October 22, 2010 at 8:28 am |
Did both in less than a minute
October 22, 2010 at 8:54 am |
Both, no problem, although I’m no sure my solution to the first is going to be accepted. Perhaps a minute total, mainly to saw if there are alternatives to the first (my solution, properly speaking, was found in just a few seconds, due to sudden attack of dyslexia… sometimes they came handy).
October 22, 2010 at 9:33 am |
1st one took around 10 minutes off and on then kicked myself when I found it. 2nd one was about 20/30 seconds
October 22, 2010 at 10:51 am |
Got the green shape in about 30 secs. Just cannot see the first one yet, still working.
October 22, 2010 at 10:57 am |
I think I’ve got an answer to the matchsticks now so that’s about 6 mins.
October 22, 2010 at 11:01 am |
First one only took a few seconds.
Second one took a couple of minutes.
October 22, 2010 at 11:13 am |
I got them both so fast that they hadn’t even been invented when I got the solution, and I was younger when I finished than when I started and I’ve solved next week’s too.
October 22, 2010 at 3:09 pm
My experience was similar, but I solved it so fast that I’m actually commenting on how to solve the puzzle that will be set in three weeks time.
I can’t believe the answer was blancmange….
October 22, 2010 at 11:25 am |
The green one came fairly quickly after a bit of squinting at it. For the CAT one, I have a solution but it leaves one of the letters a bit lopsided and involves a final step that I suspect isn’t allowed.
The “magic squares” demo is mind-blowing. Surely the guy in the crowd is a plant? Otherwise, bravo. In fact, bravo anyway!
October 22, 2010 at 11:31 am
Oh, got it. If I’m right, perhaps the preamble is a little misleading, though it reminds me of the word-based puzzles (think SALE SALE SALE SALE and TIMING TI-MING) that were posted here a year or two ago.
October 22, 2010 at 11:35 am
In fact, it’s possible to do the same thing by moving only one match.
October 22, 2010 at 11:30 am |
I shocked myself how quickly I got the first one. Once i figured out the A the rest fell into place. I was on such a high that looked at the second and answered that once instantly too…
Yes I Can you draw one line hat will divide the figure into two identical parts.
We will see if i am right when i try to do it later today.
October 22, 2010 at 12:24 pm |
The first one I got quickly, the second took a couple of minutes.
October 22, 2010 at 12:30 pm |
1: 10 seconds
2: 5 minutes
As for the magic square, Richard did the same trick at TAM London last weekend and the guy in the audience also shouted 64. Hmmm? Still impressive though.
October 22, 2010 at 5:20 pm
Stooge! I noticed this too, but didn’t know whether to be a whistle blower or not. I was suspicious at TAM when it turned out that Martin’s date of birth happened to add up to 64. I also remember a discussion (between Richard and Andy Nyman?) saying that professionals know a trick is good if the only way they can think of doing it is by using a stooge. As Brian Dunning would say, if it looks too good to be true, be skeptical!
October 22, 2010 at 12:37 pm |
Got cat down in just a few moments.
There’s a more trivial solution to the magic square given they shouted out 64: Just put 16 in each box.
_Then_ if they shout that’s cheating, ask for a harderer number.
October 22, 2010 at 1:42 pm |
Got number 2 in 1 sec. Now thinking about #1.
October 22, 2010 at 1:45 pm
Ok got #1 too, with a little trick though.
October 22, 2010 at 2:18 pm |
A couple of seconds for the first one, a couple of minutes for the second (it helps to break it down to individual squares).
Nice trick with the magic square, though something tells me ’64′ wasn’t an entirely random starting point…
October 22, 2010 at 5:30 pm |
Got both of them pretty quickly. Maybe 10 seconds for CAT, 30 for the green shapes.
October 22, 2010 at 5:34 pm |
Got the second one in maybe a minute or so, still can’t for the life of me work out the first one.
October 22, 2010 at 7:59 pm |
Matches in seconds and figure 2min.. until I used a paper and a pencil
October 22, 2010 at 8:01 pm |
OMFG that vid is crazy! musta taken 4 eva 2 fing sum1 it’d work with! hi-fiv e wiseman!
October 22, 2010 at 9:04 pm |
Sorry, no chance ! If i want to solve it, i have to spend a lot of time to do that…..
October 22, 2010 at 9:09 pm |
The Vid about Martin Gardner: How did you do that ? Are you controlling the whole internet ? Are you Mister Google ?
October 23, 2010 at 12:16 am |
[...] It’s the Friday Puzzle! Two great Martin Gardner puzzles this week…. 1) Can you change 100 into CAT by moving just two of these [...] [...]
October 23, 2010 at 1:56 am |
Hi it took me less than a minute to solve them both
October 23, 2010 at 6:13 am |
Getting a late start on the puzzle this week but…..got both in about five total including using matchsticks and cutting out the green shape just to make certain and cleaning up my mess and yep both right…..I think we have done the second one before or one very like it or maybe an other life time…very fun and now must find something else to do with my time….better work on some post for later…. or sleep…or watch movie…..just ramblin’ again…lol….
October 23, 2010 at 9:08 am |
Got a solution – though a bit weak – for CAT and nailed the shape also. Took a few minutes each and needed to draw out the shape first.
I saw the 64 Magic Sq at TAM too and was so impressed I went home and googled the trick so I can do it for my Dad’s birthday. I think I can manage any magic square now, with practice, but not with all the extra info, yet. 64 both times is suspicious, but it could be a co-incidence? 1 in 100 chance and people must be bisaed towards certain numbers so in fact better than in in a 100 in reality?
October 23, 2010 at 11:02 am |
YES I worked out puzzle number 2. Drew out 16 copies of the shape, marked out some similar areas on the 1st copy, narrowed it down to 1 line on the 2nd copy, looked at it for a few seconds, then realised:THATS IT!
October 23, 2010 at 5:55 pm |
Just a few seconds for each puzzle. I had seen something similar to the first one before.
October 23, 2010 at 8:05 pm |
I just give up of trying to find conventional answers to this kind of puzzles, that make me a lot more easy to deal with them.
hum, less than one minute to find out both.
October 24, 2010 at 12:40 am |
About 2 seconds for the second one, 15 for the first.
I also have a solution for the first moving only one matchstick.
October 24, 2010 at 1:17 am |
[...] It’s the Friday Puzzle! [...]
October 24, 2010 at 3:23 pm |
Number (1) seen it before, Number (2) I’ve got an answer but it doesn’t seem to be cryptic enough to actually be the answer. (Video) how lucky that the guy said 64!!! Can you do another one with 65?
October 24, 2010 at 5:08 pm |
The second one took a few seconds of looking. The first was a lot harder, until I remembered a certain pencil-nosed Martian.
October 24, 2010 at 9:21 pm |
solved in 8 minutes.
October 24, 2010 at 10:37 pm |
30 seconds on number 2.
Infinity on number 1.