## Sunday, October 28, 2007

### The infamous brick puzzle

Difficulty: 2 of 10

Here's a puzzle "classic". I call it the infamous brick puzzle, and you'll see why.

There are actually two variations on this puzzle.

Variation 1:
Draw a curve without lifting your pencil such that you pass exactly once through the top, bottom, right, and left sides of each of the five rectangles. No passing through corners.

Variation 2:
Draw a curve without lifting your pencil such that you pass through each line segment exactly once. Note that the lower left and lower right rectangles each have 4 line segments surrounding them, while all the others have 5. Again, no passing through corners

There are a lot of stories I've heard of people obsessing over this puzzle, trying to find the solution. Once I read a story by this guy who was given this puzzle in elementary school, and he obsessed over it well into adulthood. This puzzle is pure evil, I tell you. I don't even know why I'm posting it--I guess I must have an evil streak. It's the kind of puzzle whose author probably deserves to have his hand cut off. Well, I guess it's not that evil, since no communication tricks are involved.

Oh man, speaking of the -gry puzzle, that one's even worse. Supposedly, it first appeared on a radio show, and it got repeated everywhere, only when people repeated it, the words got mixed up in a way such that it was unsolvable. Um, yeah... these are the sort of stories you pick up when you're a puzzle enthusiast.

Anyways, it's actually a pretty easy puzzle. See the solution here in the comments.

Anonymous said...

don't post the solution yet, i don't have enough time to look at it right now, i have too much work.

Anonymous said...

ok, i looked at it, I'm stuck, can you show me the solution?
It looks impossible

Anonymous said...

Yes, I'm definitly sure that I think it's impossible...

miller said...

Solution time!

Variation 1:
There are two bricks on top, and three on bottom. Therefore, the total number of times you must pass through the horizontal line must be both three and two. Last I checked 3 isn't equal to 2, so this puzzle is impossible.

Variation 2:
For each rectangle, unless you started or ended the line within the rectangle, there must be exactly one exit for every entrance. So except for the starting rectangle and ending rectangle, you must enter and exit each rectangle an even number of times. However, there are three rectangles that require an odd number of entrances and exits. Therefore, this variation is impossible as well.

So, I hope no one has wasted too much time thinking that there must be a solution.

Anonymous said...

HAH! I knew it!

Anonymous said...

My husband has been trying to figure this out for 17 years or so. He told me about it today, I tried it a couple of times, said "screw it" and googled it. THANK YOU for setting me straight so I don't spend eons over it! Shhh....don't tell my husband though!

Anonymous said...

My law teacher said that his teacher solved this puzzle in grade 6, but he didn't write it down. Whether this is true or not, I'm not sure, but everytime I try, It's one line that always gets missed!

Anonymous said...

Im just throwing this out there but i found a solution to this puzzle...

its REALLY stupid but i did find a solution to it

Unknown said...

I dont believe you found a real solution but let me see your spin on it anyway

Anonymous said...

Off and on for 20 years I've tried to solve this puzzle. Thanks for setting me free. My 6th grade math teacher should be punished for giving this out, saying there was a "solution" and never letting us know that the solution was that it is impossible. Just pure evil.

Anonymous said...

Actually there is a solution to the five brick puzzle, proposed by the German mathematician Euler. He maintained that since a line has only one dimension (length), it can be FOLLOWED without CROSSING it. Try this "route": Draw the five bricks and number each line segment for reference purposes, starting with the horizontal line segments, working left to right from the top left hand segment. There are 9 horizontal segments. Then starting with the upper left vertical segment, number the vertical segments. There are 7 vertical segments, for a total of 16 line segments in all.

Start inside the upper right-hand brick and exit through segment 2; re-enter across 12; enter the lower right-hand brick across 6,and exit across 16; re-enter the lower right brick across 9 and exit (thereby entering the centre-lower brick) across 15; continue across the brick and exit across 14, thereby entering the lower left hand brick; exit the brick across 7, re-enter across 13, and exit across 3, thereby entering the upper left hand brick; exit the brick across 10 and re-enter across 1 and exit again across 11, thereby entering the upper right hand brick; note there are only three line segments not crossed yet: 4, 5, and 8; exit the brick across 5, thus entering the lower centre brick and exit across 4 thus entering the upper left hand brick; now comes Euler's solution: FOLLOW line segment 14 from the top (inside th eupper leeft hand brick) to the bottom thus exiting the puzzle and then cross segment 8 from the outside, thus re-entering the lower centre brick. You have completed the puzzle.

miller said...

Nice, but in my statement of the problem, I ruled that you can't go through corners. In your solution, you've gone through the corner at the intersection of 3, 4, and 14 (as well as another corner at 7, 8, and 14). Anyways, if we were allowed to go through corners, why not just go through the intersection of segments 10 and 1? That would also solve the problem just as well.

But I don't mean to steal away any sense achievement you got out of it. I say take what you can get from this evil puzzle and run.

Mark and Cari said...

I have a solution to this one. It involves 1 horizontal fold of the paper and an unfold during the moving of the pen. Just be sure not to lift the pen! :)

Anonymous said...

This is impossible!! My grandfather gave it to me and said he would pay me \$500 if i solved it

Anonymous said...

you guys are all freaks for trying this out it doesn't even work DONT GIVE UP YOUR DAY JOBS

Anonymous said...

Football's beta why bother ya self with dat problemo

Mark and Cari said...

Once again, not impossible. Fold the paper over the horizontal line (actually, it's a Z fold) and you can then figure out how to do it by unfolding after crossing one line. You've got to think outside the box, or in this case, the brick!

Anonymous said...

My math teacher said that she has been trying to solve this puzzle for 50 years- every since her elementary school math teacher showed it to her, saying it was impossible. But my math teacher didn't believe her and is still trying to figure it out...

Mark and Cari said...

Has no one tried my way yet? It is definitely NOT IMPOSSIBLE, and VERY POSSIBLE!

miller said...

Mark and Cari,

I'm happy you found a solution you like, but please, no all-caps nagging. Personally, I think it is just as satisfying, and involves just as much thinking outside the box to figure out that the puzzle is indeed impossible (given a few implicit assumptions, such as no folding paper). Most people would consider folding the paper to be cheating. It's hard to cheat oneself into self-satisfaction!

In short, I appreciate your attempts to help the escapees of this mindtrap, but I don't think it will work!

Mark and Cari said...

In my opinion, there can be no assumptions in a mind-teasing puzzle. The instructions were very clear, and I've never seen a version with different instructions. But I'll agree that "assuming" no folding, it is impossible. The folding bit is where the thinking outside the box comes into play!

miller said...

As someone who has written puzzles, I must respectfully disagree that there are never any implicit assumptions. When I write puzzles, I always expect people to give me the exact same answer I thought of, regardless of whether there are any other valid solutions! (I kid, I kid.)

Anonymous said...

hello im a 15 yr old boy been trying to do this puzzle for 2 years my art teacher done this puzzle in front of me and i was really shocked then he tore it up and said he would give any pupil £25 if they could do it and he gave me a clue a butterfly and sliced bread so use them clues and try to find out how to do it

Unknown said...

A butterfly and sliced bread? Why didn't I think of it earlier!! It's all clear. Starting in the top right exit through segment G2. Re-enter through segment A1. Complete a small horse-shoe shape through segments a thru e covering sub-segments 1-6. With this covered, it should become obvious that you are left with two segments reachable through a straight line.

Hope this helps (p.s. in my 58 years of puzzle writing, I have never managed to find anything so intellectually refreshing.)

Remember, there is no charge for awesomeness.

Anonymous said...

yes, 17 years is my count on trying, please tell me there is a solution. please? please? I am obsessed! ahhhh!

Anonymous said...

well me and a couple family members have been trying to figure it out for the past 2 an a half hours, so finally i said why not just look it up on the coputer because there has to be a way, come to find out... it is impossible!

Anonymous said...

can some one like draw up the answer and like post it on google pictures or something coz the whole number thing is super confusing

Anonymous said...

Cant you just put the picture up there and let me copy it!!!
I mean it is alot more complicated when you type it like that. D;<

Anonymous said...

wtf this puzzle is gay. my math teacher says he knows its possible without cheatiing. there are 2 billion 900 thousand ways to do it wrong and 1 way to do it right. so if u say its impossible email james hughs or LMB

Anonymous said...

This is they gayest thing ever. I tried some of the solutions on here but they are just all garbage. You people are dumb and can LMB.My Math teacher it going to give us 50\$ if we do this thing, so why doenst some one just post a dang picture of it so we can copy it and i can get some money.

Anonymous said...

hey anonymous i am in james hughses class to ind i think your freakin riight
guy who said somthing about a butterfy and horse shoe should just post the freakin answer why hasnt any one thought of it? yet they are all just gay. and who are you? this is S. B. those are my anitials post yours or just tell me who you are if you realize who i am

Anonymous said...

i am obsessing over this thing an james said there is an answe so just post it already!

miller said...

If you are so convinced that it's possible, consider this: Some people say it is possible, but they never provide evidence. I say it's impossible, and I showed you the full proof.

There's perhaps a lesson in all this: Question all authority.

Anonymous said...

im soru miller but i think that anounoumas in augusst at 1 57 was right i think thats the way

Anonymous said...

does any body know what the actul name of this puzzle is called. I need to know

miller said...

As far as I know, this puzzle does not have an official name. Most puzzles don't.

Anonymous said...

Some body should try and find a name for this puzzle because it will help me so much.

Anonymous said...

Wheres the picture of it done at

miller said...

My name for it, "The infamous brick puzzle" is just as good as any.

There is no picture of the solution, because the solution is that it's impossible.

Anonymous said...

Dude that aint the name. Somebody told me there was a specific name but they wont tell me so i need to know the specific name.

Anonymous said...

I wasted 15 years and \$5000 on beating i could do this puzzle PLZ let there be a way to solve this puzzle PLZZZZZZZZZZZ

Anonymous said...

its too hard i do it and one line is always left!!!!

Anonymous said...

Can be done. can be done.

Anonymous said...

draw the bricks very small and get a huge marker pen and draw one huge line over the entire thing. simple.

Anonymous said...

They have this puzzle at the bottom of the Patrona Towers in Kula Lumpur, I went away annoyed I couldn't solve it. However it was a fixed wooden structure with pegs in the corners and string, so a fold was impossible, therefore rendering the solution impossible also.

Anonymous said...

Can I tag another puzzle that I've been struggling with on this thread?:

You are given 6 identical sized wooden blocks to fit into a box. The 6 wooden blocks are 2x2x1 in size (like a square shaped book) and the box inside area is 3x3x3 (like a Rubix Cube). Can it be done? I don't have a solution, can anyone help?!!

miller said...

That's the first I've heard of a physical implementation of this puzzle. I bet most people in Kuala Lumpur would try to tell you it was possible (keeping the legend alive).

The six wooden blocks puzzle can be done. No unusual block orientations are required, but the solution is difficult to describe without a picture.

Anonymous said...

I solved this last night with the parameter; that each of the 16 segments must be crossed only once with a single line of any shape. The friend who showed me this last night has not found anyone in 15 years that could solve the puzzle. Took me about 2 hours of playing with to figure out that could be solved. Another 1 1/2 hours to get close. Prayed and asked the Big Guy to make me smart enough to get it and I did get it with his helpafter about another 1/2 hour. The
solution is quite simple and elegant once you see it. Involves a 3/4 circle in the centre intersection and another 3/4 circle in the bottom 2nd vertical bar and the baseline. That should be a decent hint for someone else to get it.
Clive cliveapps@gmail.com

Anonymous said...

why can people not just post a picture of the solution instead of trying to describe it

Anonymous said...

Yep you guys there are a few possible ways here. Really one that hasn't been mentioned thus far.

Take a big sheet of paper and draw our diagram, and do it witha small pencil. Then poke the whole pencil through, and it's pretty darn easy.

:). It is impossible to do for the reasons shown by Miller... without manipulating the paper, that is.

Anonymous said...

If you go straight up the vertical line between the two top bricks you can do it, If that is against the rules then you cant.

Anonymous said...

my mum has been tryin to do this 4 26years after her maths teacher mr lewis at oakbank school give her it she has onli to this day found it its impossible (idiot)

Unknown said...

This torture device is impossible to solve. There are about 15 million different combination's. Its simple there are not enough exits to achieve the solution, with how many entrances your required to pass through. Math it out, its fact. A colleague of mine wrote a computer program to try and find a solution to this, it is impossible to solve according to the rule set provided. But it is an excellent method for exercising the mind in unusual ways, find your own solution and know that with the given parameters this is not solvable.

Anonymous said...

its verry simple. the solution is imposible 2-d but maybee posible 3-d. thats what my geography teacher said and he will prove it at the end of the year. also I am copying off a dude who he says is on the last layer. Put dots where all the line segments end and dashes in the middle of the line segments. then remove the lines. thats how far i got. He also said something about morse code.Im not sure though he's crazy.

Anonymous said...

If the solution is possible prove the possibility. email:jessiebee123@yahoo.com

Anonymous said...

the only way it can be done is to move the top brick over to 1 size bigger that's the only way

kayeligh said...

all i have to say is me and my two little sisters my uncle and my grandpa have spent a lot of time trying to figure it out so we looked it up and it dosent say anything
* So back to the drawing board

Anonymous said...

the answer is, for example if u want to pass through each line segment once through the puzzle, u cant , there are an odd number of line segments if there were 8 10 12 etc. u would be able to do it its like the puzzle with 17 door ways and u r supposed to go through the house inside and out and go through all dorr ways without going through one twice, it's impossible, there has to be and even # of lines of whatever, really simple really

Anonymous said...

okay, here's one thing the author forgot to post. you CAN NOT go through the same line twice. Once you enter you may not exit through the same opening. It is possible but you just have to be creative

Anonymous said...

ok so like the other one said alot of people say it can be done....but there is no prof. so until i see the solution it is false.

p.s Vampires rule!!!

Anonymous said...

I obsessed with this problem for months. Finally wrote a computer program to run all iterations... took many weeks of keeping my spare laptop running in the closet to finish... had to rewrite several times because my status indicator would predicts many months to complete... no solution.

miller said...

LOL. That story sounds so fake. It would not actually take that long for a computer to run through all possibilities for this puzzle.

Chris said...

It was written in uncompilable BASIC... my one and only language. It was executed on a 2002 Dell Laptop. You write something faster in BASIC and run it on the same laptop...
There are many iterations.
If you challenge me, I'll go find the code...

Thomas said...

Miller, you said that variation 2 is impossible 'unless if you started or ended the line within the rectangle'. Does that mean it's possible if you start or finish inside a brick, while doing variation 2? If so, wouldn't it count as a valid solution, seeing as there's no indication of where you're allowed to start/end and it didn't seem implied? If there's no solution with this method either, it'd be nice to know. Cheers.

miller said...

No, that's not what I said. I said for each rectangle, unless that rectangle was your starting or ending point, there must be an even number of times you cross the edge. Unfortunately, there are three rectangles that need an odd number of crossings, and you can only start in one and end in another. Therefore, it's impossible.

Anonymous said...

It's definitely possible. I solved it. Check this out: Start in the bottom middle, go left, up, then back down to bottom middle, top left, down to bottom left, out left side, up to top right(through left side), up through the top left, back down through top right, out top right side, in bottom right side, out bottom right, in bottom middle, go left and then go down.
Solved. Easy as pie.

Anonymous said...

http://lolpics.se/20202-impossible

Here is a pic to prove everyone that tried to say it's impossible is absolutely retarded.

miller said...

That explanation is utterly unreadable, and that picture is missing a door. But thanks for trying!

Anonymous said...

My teacher assigned my class a brain teaser and with a little internet searching I found this "infamous brick puzzle." The only difference is that the one my teacher gave us was a circle rather than a rectangle, giving it 12 separate line segments. Is this equally as impossible as the brick, my teacher swears he knows the answer.

Anonymous said...

It can be done but you have to start on the out side and you will finish inside turn it upside down, start by going Up through the bottom of the first rectangle, then left, then Circle right, then down, Circle back up and then the left and out the top, go straight right then up circle around the far right side then down and right, circle around the bottom and come up through to both lines then circle around down, and right

Anonymous said...

I've been wanting to show this puzzle to a group that I help mentor, but I would like to present the formula which explains why this is impossible after their attempts. Educational aspect.

Tammy Taylor said...

Okay folks, since 1956 from my math teacher; that's like 56 years. Just showed it to my grandson on Sunday the 6th; then I found your Blog this Tuesday the 8th, in the morning. There are some great ideas amongst you.

Yes, I have tried to find a solution, for 56 years, a little scribble now & then, but... no proper solution yet.

And then... My just found, this Tuesday morning, 8th of May, a most probable solution: Since it is called the 5 Brick Puzzle, so be it; draw 5 bricks, do not let bricks touch, leave room for the mortar; all lines can now be crossed, as each brick has 4 line segments.

Or, draw the 5 bricks in perspective 3-D.

Nailbreak

Anonymous said...

lol, my science teacher offered 50 extra credit points to the first person to get it... i bet he knew the solution

Anonymous said...

I started working on this puzzle when I was 12 yrs old. There was a professor from Washington state offering \$300,000.00 to the person that solved it. He said that it was mathematically possible. And with that I have now been working on this puzzle for 24 yrs. I have hundreds of notebooks filled with failed attempts . I just passed this curse onto my 12yr old son. So far he is obsessed with it, like I was. What have I done.......

Larry Hamelin said...

Poor bastard!

This comment has been removed by the author.

I Just found a solution!!!
http://i.imgur.com/cztZL.png
Found using MSPaint for easier "erasing" of mistakes

9/29/2012

Do I get that \$300,000 you talked about?

miller said...

No, you went through the upper right horizontal wall twice.

Anonymous said...

my teacher gave us a VERY similar puzzle, basically the exact same thing, but the 4 outermost corners are rounded out to form a circle. one of my classmates claims to have solved it, but refuses to show me the answer. is it possible?

Anonymous said...

My ex-gf gave this to me to solve... she never told me it was impossible... oh, the irony...

Unknown said...

If this is bricks why look at it in these dimensions?

Unknown said...

so in a third dimensional for it would have two bricks with 12 sides each on top and 3 bricks with 12 sides each on bottom - sry if this is not very smart im only 15 yrs old

Unknown said...

and i was wondering if you could use the line as representing the forth dimension? time

Unknown said...

for me the butterfly represented the theory of the butterfly effect which of course had a huge involvement in time, and the bread being not in 2 dimensions representing the 3rd dimension needed

Unknown said...

my main question is when does the 5th dimension come into play?

miller said...

I'm afraid I don't understand the question.

Unknown said...

5th dimension....space.

Unknown said...

and i of course am speaking of the bricks as being objects in the real world as literal bricks and the line being time passing through them as they would indeed have more sides, perhaps making it more mathimatically possible.

Unknown said...

but remember im only 15 so my math and physics and whatever arent the best and i kind of dont agree with most science yadda yadda yadda. just giving it a fresh thought

Unknown said...

the closest i get to liking science is liking asimov.

Unknown said...

but of course his science is just as real as our science.

miller said...

Leave fewer, longer comments, please, or I'll have to trash them as spam.

Unknown said...

do you understand it though?

miller said...

They are not literal bricks, they are rectangles.

Anonymous said...

I was given this puzzle in middle school. I have been obsessed with it since then.
Got my kids hooked. Stumped my brilliant husband.

I even tried finding the teacher who first showed it to me....

I will spend the rest of my days trying to figure it out.

Anonymous said...

This was given to me in school also in geometry explained one continous line through all segments once with out missing any. Took six months and was told answer a friend and i came up with was correct. Sheet up paper with drawing represents 1 2d plane punch holes threw each segment and feed string (one continuous line ) through holes thus crossing the lines from different planes never crossing same line twice twice in the single 2d plane. Solved second solution could be bending the 2d plane so that all lines in brick puzzle line up in different planes then pass a single line through all lines more of a bending space time answer anyways tjays my take on it.

Anonymous said...

Done! I did it it's really was hard, but i did it :) i could tell you solution, but then everyone would know it and i would not be interesting :) and i only did it in 132 days :) but it is not easy...

Anonymous said...

No thats not solution :/ i have the real one..

miller said...

wrong on both counts............

miller said...

Its impossible guys don't be stupid: http://en.wikipedia.org/wiki/Five_room_puzzle

miller said...

I think it's physically impossible !

miller said...

The corners aren't lines.(:

miller said...

miller said...

It is

miller said...

You have to draw it on a donut or bagel with the hole of said pastry food in the centre of 1 room only.

miller said...

So I did it in one go...
http://imgur.com/X10cr28

miller said...

You missed a couple line segments in the middle. Try again!

miller said...

I have a solution, how can I post the picture

miller said...

Pictures can be e-mailed to me at skepticsplay at gmail dot com, although they won't appear publicly that way. To post publicly you'd have to use an image hosting service and link to it.