BrainDen.com - Brain Teasers

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## Popular Content

Showing content with the highest reputation since 11/08/13 in all areas

1. 2 points

## A Simple Riddle

In our circles you may find A laugh, a wink, a grin But pressure us we'll likely snap And send away our kin. We don't do much, we go to pot Such simple ones are we But with your hand we take command Or from you we will flee.
2. 2 points

## Folding paper

Agree. When I hit the send button, I realized my thinking was too simple. But instead of deleting my post (moderator privilege) I left it to take its licks.
3. 2 points

## Simulating an n-sided die with two coins

Say we want to simulate an N sided die.
4. 2 points

5. 2 points

## Upside Down Cake

(This puzzle is from a blog called By Way Of Contradiction.) Imagine you have a circular cake, that is frosted on the top. You cut a d degree slice out of it, and then put it back, but rotated so that it is upside down. Now, d degrees of the cake have frosting on the bottom, while 360 minus d degrees have frosting on the top. Rotate the cake d degrees, take the next slice, and put it upside down. Now, assuming the d is less than 180, 2d degrees of the cake will have frosting on the bottom. If d is 60 degrees, then after you repeat this procedure, flipping a single slice and rotating 6 times, all the frosting will be on the bottom. If you repeat the procedure 12 times, all of the frosting will be back on the top of the cake. For what values of d does the cake eventually get back to having all the frosting on the top?
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8. 2 points

## Crazy People

eq ( 1 ) Study = not failed eq. ( 2 ) not study = failed add eq ( 1 ) & ( 2 ) study + not study = fail + not fail study ( 1 + not ) = fail ( 1 + not ) study = fail Then why should we study??
9. 2 points

## Blonde Jokes

this one is pretty cute! Blonde v.s. Lawyer a lawyer sitting on a plane next to a Blonde want to pass some time and turns to her and says, "how about a trivia game, if i ask you a question and you get it right I'll pay you 10 dollars, and if you get it wrong you pay me 1 dollar. then you ask me a question, with the same conditions." blonde says, "no thanks, I'm reading a book." the lawyer says, "okay how about this, 20 dollars for getting right for you, and 20 dollars for getting wrong for me." the blonde rolls her eyes and says fine. the lawyer asks, "whats the distance from the earth to the sun?" the blonde hands him a dollar. then the blonde asks him, "what goes uphill with 3 legs and down hill with 4?" the lawyer blinks for a second and says " i have no idea, i guess you win that round." then hands her 20. "okay my turn again, i am curious, what does go up hill with three legs and down hill with 4?" the blonde hands him another dollar.
10. 2 points

## One Up Me

What happens in quantum statistical thermodynamics stays in quantum statistical thermodynamics...b/c no one else cares.
11. 2 points

## One Up Me

Out of the frying pan and on to the floor. Back into the frying pan, let hope none of the guests saw.
12. 2 points

## Crocodile Sophism

I would think that the only way to make ANY sense of the situation is for the woman to repeat back to the croc EXACTLY what he said to HER: "If I guess right, you'll give my baby back, if I dont, you'll eat him. That's what you'll do to him." He'd have to return the baby, because she's CORRECT NO MATTER WHAT. Eh? hehehe
13. 1 point

14. 1 point

## Worth the Weight

4 light ones/48
15. 1 point

## Forgotten District II Mafia

@flamebirde because Molly was playing off of the word easy, which is a popular Commodores song. No other reason
16. 1 point

## UN Mafia III

Hey guys, sorry I'm here. Didn't realize I could talk when I was trapped and then I'm having issues accessing the site on my phone. I'm on through Firefox now and it works better than Chrome I guess. I will catch up at lunch and see what I can contribute, hopefully before the night ends in case I was mercy/mod killed.
17. 1 point

## UN Mafia III

@Thalia, good points. I've played only a few Mafia games. I wish I had accepted Unreality's invite to play, back in the day, and learned it better. Coupled with a hope for a few more games to follow this one. My comfort zone is math and logic, where all the needed info is provided, just needing insight and clear thought. This is more fun, actually, and with experience I might get better. Or, I'm a very slippery guy and everything I just said is garbage. . When does the night end?
18. 1 point

19. 1 point

## 5x5 table with unique properties

Example : (2,2) cell (red) is 3, so it is surrounded by 3 unique numbers (1,2 and 3) (4,4) cell (blue) is 4, so it is surrounded by 4 unique numbers (1,2, 3 and 4) The Question 3 . . . . . . . . 2 . . . . . 2 . . . . . . 3 . . Fill in the blanks so the table has the same unique properties. I think I have it:
20. 1 point

Description:
21. 1 point

## Light Bugs

There are multiple solutions:
22. 1 point

## Bus Schedule

plainglazed noted that the investigator measures the entire time interval between buses; k-man was first to hit on the crux of the correct analysis (getting the mark); and plasmid beautifully and comprehensively reminded me again that I used to know how to evaluate integrals. Uh, rephrase. Has reminded me that I no longer recall how to evaluate integrals ... without looking them up. Kudos to all. The idea is that Here's the quick analysis provided by the Quora article I mentioned at the top: The idea is similar to BMAD's puzzles about random arcs on a circle enclosing a particular point. The arcs correspond to interval times and the point corresponds to the sampling process.E[T]=∑ttp(t)=10260+35260+10260+5260≈25
23. 1 point

## Crazy People

I took me a little while to figure this out. Now that I did... ...I still can't stop laughing!
24. 1 point

## Walking on a lattice

A random walk on the three dimensional integer lattice is defined as follows. The walker starts at (0, 0, 0). A standard six sided die is rolled six times. After each roll the walker moves to one of its six nearest neighbors, according to the following protocol: if the die rolls 1, 2, 3, 4, 5, or 6 dots the walker jumps one unit in the +x, −x, +y, −y, z, −z direction respectively. Find the probability that after the sixth roll the walker is back at its starting point (0, 0, 0).
25. 1 point

26. 1 point

## Can anyone help me find this type of logic questions?

Hi Jelly, and welcome to the Den. I searched on the Web a bit, and did not find puzzles of this type, but they may be out there. If anyone does find them, a link can be posted to this Forum: http://brainden.com/forum/forum/9-other-mind-boggling-stuff-on-web/
27. 1 point

..........
28. 1 point

## A simple multiple-choice test

1. The first question with B as the correct answer is: A. 1 B. 4 C. 3 D. 2 2. The answer to Question 4 is: A. D B. A C. B D. C 3. The answer to Question 1 is: A. D B. C C. B D. A 4. The number of questions which have D as the correct answer is: A. 3 B. 2 C. 1 D. 0 5. The number of questions which have B as the correct answer is: A. 0 B. 2 C. 3 D. 1
29. 1 point

30. 1 point

## Random bullets

I hope I got it:
31. 1 point

## Relatively prime

yeah I believe it is actually 6/pi2.
32. 1 point

33. 1 point

34. 1 point

35. 1 point

## The Stuff

Want me to help out? It's very punny ...
36. 1 point

## Sacrifice Mice

If they worked out the code beforehand...
37. 1 point

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40. 1 point

## The Magnetized Coin

hmm, 4 is possible not sure about 3.
41. 1 point

## Can you decript this?

That sucks, I don't have many friends myself. Aaryan's point, though, is that asking us to solve it for you is cheating. But since you got the hint of using a 9x6 matrix, I'll at least do you the favor of putting the message in a 9x6 matrix. WH3TEE HERWDN A2OO7T TSO6AY 0QTHN9 IU4UDF SAON8I 1RFDTV TE5RWE Hopefully you can see it now. Good luck with the competition!
42. 1 point

43. 1 point

## Human origin" according to my own theory"

Personally, the original reason I believed in God is that an adult told me he existed when I was little and, being little, I took their word. But over time, I've listened to people talk about their experiences with God and seen it with others. I think I've seen Him get me through a lot of stuff the past few years that I don't think I'd have been able to make it through alone. You could say that I got through them because I worked hard, or just because believing in a higher power has some effect psychologically, or that there were coincidences involved, but when I put it all together, those reasons just don't work for me. But if I had to give just one reason that I believe God is real, it would be that He told me so. Audibly.
44. 1 point

## Lychrel

Code: #include <iostream> #define BUF_SIZE 100 using namespace std; void putInArray(int num, int* buf){ for(int i=0;i<BUF_SIZE;i++){ buf[i] = num % 10; num = num / 10; } } bool isPalindrom(int* buf){ int i=0, j=BUF_SIZE-1; while(buf[j]==0 && j>0){ j--; } while(i<j){ if(buf[i] != buf[j]){ return false; } i++; j--; } return true; } void applyIteration(int* buf){ int i=0, j=BUF_SIZE-1; while(buf[j]==0 && j>0){ j--; } while(i<=j){ int temp = buf[i] + buf[j]; buf[i++] = temp; buf[j--] = temp; } for(int i=0;i<BUF_SIZE-1;i++){ buf[i+1] += buf[i] / 10; buf[i] = buf[i] % 10; } } bool isLychrel(int* buf){ for(int i=1;i<50;i++){ applyIteration(buf); if(isPalindrom(buf)){ return false; } } return true; } int main() { int buf[BUF_SIZE]; for(int num=0;num<10000;num++){ putInArray(num,buf); if(isLychrel(buf)){ cout << num << " is Lychrel " << endl; } } }
45. 1 point

## Crossing the bridge

A group of four people has to cross a bridge. It is dark, and they have to light the path with a flashlight. No more than two people can cross the bridge simultaneously, and the group has only one flashlight. It takes different time for the people in the group to cross the bridge: Annie crosses the bridge in 1 minute, Bob crosses the bridge in 2 minutes, Caren crosses the bridge in 5 minutes, Dorothy crosses the bridge in 10 minutes. How can the group cross the bridge in 17 minutes?
46. 1 point

47. 1 point

## One Up Me

You can shoot the gun, but...add the bullets, first... ...noobs...
48. 1 point

## The Bible

Yeah that was the rain. The ark was in the water for about 150 days though.
49. 1 point

## Honestants and Swindlecants II.

Honestants and Swindlecants II. - Back to the Logic Problems Afterwards he meets another two aborigines. One says: "I am a Swindlecant or the other one is an Honestant." Who are they? This old topic is locked since it was answered many times. You can check solution in the Spoiler below. Pls visit New Puzzles section to see always fresh brain teasers.
50. 1 point

## 1000 people in a circle

Person 1 is left behind there would be no one to kill him
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