Riddles thread

[Tim Reynolds]

Oooh someone posted a math riddle. When does 3 + 4 = 111?

When you're working mod 104

When does 9+4=1.

When you're working mod 12

How about the flaw in this "proof"?

assume x > 0 (no tricky divide by zero nonsense)

x^2 = x^2 ; identity, also it is true on the interval x > 0

x^2 = x*x ; (expand the exponent)

x^2 = x + x + x + ... + x ; (x instances of the variable x) ; expand the meaning of multiplication

d/dx (x^2) = d/dx (x + x + x + ... + x) ; (x instances of the variable x) ; differentiate both sides

2*x = 1 + 1 + 1 + ... + 1 ; (x instances of the number 1) ; evaluate the derivative, remembering that the derivative is a linear operator.

2*x = x ; (add together the x instances of the number 1)

2 = 1 ; divide by x, which is ok here because I differentiate on the interval of x > 0, and because of this restriction diving by x has a meaning and is not undefined

2 must really equal 1 :rolleyes:

Chris

(serious this time) x^2 = x + x + x + ... + x is only valid for positive integer values of x. To take the derivative of the right side, it needs to be defined at all real values of x (well, to be precise, it needs to be defined in some neighborhood about whatever x_0 you're differentiating at). Since Z+ is not open in R, you can't take the derivative like that.

But 2=1 when you're working mod 1, so it all works out in the end.

 

[cmhardw]

Oooh someone posted a math riddle. When does 3 + 4 = 111?

When you're working mod 104

Wow good point, I wasn't thinking of it like that

How about the flaw in this "proof"?

false proof text here...

Chris

(serious this time) x^2 = x + x + x + ... + x is only valid for positive integer values of x. To take the derivative of the right side, it needs to be defined at all real values of x (well, to be precise, it needs to be defined in some neighborhood about whatever x_0 you're differentiating at). Since Z+ is not open in R, you can't take the derivative like that.

But 2=1 when you're working mod 1, so it all works out in the end.

Yep Tim got it! Also Tim, that last part made be actually lol. That was good

Chris

 

[Cool Frog]

Can you jump higher that a house?
I can jump higher than my house, i can jump higher than your house, i can jump higher than the white house. Why?

Houses can't jump silly. So you can jump higher than it can.

 

[Forte]

Can you jump higher that a house?
I can jump higher than my house, i can jump higher than your house, i can jump higher than the white house. Why?

Houses can't jump silly. So you can jump higher than it can.

My house can jump.

 

[Hyprul 9-ty2]

Can you jump higher that a house?
I can jump higher than my house, i can jump higher than your house, i can jump higher than the white house. Why?

Houses can't jump silly. So you can jump higher than it can.

My house can jump.

My house can jump higher than yours.

 

[Forte]

Can you jump higher that a house?
I can jump higher than my house, i can jump higher than your house, i can jump higher than the white house. Why?

Houses can't jump silly. So you can jump higher than it can.

My house can jump.

My house can jump higher than yours.

Dang

 

[CL_Pepsi]

Some man is dead 5 feet away from a rock. How did he die?
Nothing stupid like the rock fell from the sky or meteors. Hint:he's super special

 

[(R)]

the rock punched him to death get it dwane "the rock" Johnson

 

[brunson]

Spoiler

Is the rock kryptonite?

 

[Ranzha]

Another riddle for you all!

|O| | | |
| | | | |
| | | | |
| | | |E|


In this theoretical prison there are 16 cells in a four by four grid. The exit is at the bottom right (marked 'E'). Diagonal travel is impossible (left, right, up and down only). Exit or entry through any other exterior wall is impossible.

Oscar is a murderer and a brilliant escapist. His cell is in the top left ('O'). He has a strange quirk and can never return to the scene of a crime.

When the warden returns one morning he finds Oscars cell empty and all 15 other inmates murdered (each cell is the scene of a crime). Are you able to plot a possible escape route assuming that Oscar had no outside help?

(This ones great because it looks really easy at a glance.)

Spoiler

I'm using this from somewhere else.

 

[CL_Pepsi]

Spoiler

Is the rock kryptonite?

Yup

 

[Sa967St]

Another riddle for you all!

|O| | | |
| | | | |
| | | | |
| | | |E|


In this theoretical prison there are 16 cells in a four by four grid. The exit is at the bottom right (marked 'E'). Diagonal travel is impossible (left, right, up and down only). Exit or entry through any other exterior wall is impossible.

Oscar is a murderer and a brilliant escapist. His cell is in the top left ('O'). He has a strange quirk and can never return to the scene of a crime.

When the warden returns one morning he finds Oscars cell empty and all 15 other inmates murdered (each cell is the scene of a crime). Are you able to plot a possible escape route assuming that Oscar had no outside help?

Spoiler

Are you able to plot a possible escape route assuming that Oscar had no outside help?

no

 

[Forte]

Another riddle for you all!

|O| | | |
| | | | |
| | | | |
| | | |E|


In this theoretical prison there are 16 cells in a four by four grid. The exit is at the bottom right (marked 'E'). Diagonal travel is impossible (left, right, up and down only). Exit or entry through any other exterior wall is impossible.

Oscar is a murderer and a brilliant escapist. His cell is in the top left ('O'). He has a strange quirk and can never return to the scene of a crime.

When the warden returns one morning he finds Oscars cell empty and all 15 other inmates murdered (each cell is the scene of a crime). Are you able to plot a possible escape route assuming that Oscar had no outside help?

Spoiler

Are you able to plot a possible escape route assuming that Oscar had no outside help?
no

Is it something stupid like "HE THREW THE DARTS AT THEM AND THEY DIED" or "HE STEPPED IN A CELL AND KILLED SOMEONE BUT STILL STAYED IN THE OTHER CELL SO IT DOESN'T COUNT AS LEAVING" or "HE SUFFOCATED THEM WITH POISON GAS"?

 

[brunson]

Another riddle for you all!

|O| | | |
| | | | |
| | | | |
| | | |E|


In this theoretical prison there are 16 cells in a four by four grid. The exit is at the bottom right (marked 'E'). Diagonal travel is impossible (left, right, up and down only). Exit or entry through any other exterior wall is impossible.

Oscar is a murderer and a brilliant escapist. His cell is in the top left ('O'). He has a strange quirk and can never return to the scene of a crime.

When the warden returns one morning he finds Oscars cell empty and all 15 other inmates murdered (each cell is the scene of a crime). Are you able to plot a possible escape route assuming that Oscar had no outside help?

(This ones great because it looks really easy at a glance.)

Spoiler

I'm using this from somewhere else.

Spoiler

The trick would be that he can return to his own cell.

 

[LewisJ]

Prisoner:

Spoiler

Returning to his own cell doesn't help at all. It's an impossible puzzle.

 

[brunson]

Am I doing this wrong?

Spoiler

Number the cells left to right, top to bottom:

1 2 3 4
5 6 7 8
9 a b c
d e f g

He starts at 1, goes to 5, returns to 1, then proceeds, 2 6 7 3 4 8 c b a 9 d e f g

I think that works.

 

[Sa967St]

Am I doing this wrong?

Spoiler

Number the cells left to right, top to bottom:

1 2 3 4
5 6 7 8
9 a b c
d e f g

He starts at 1, goes to 5, returns to 1, then proceeds, 2 6 7 3 4 8 c b a 9 d e f g

I think that works.

it looks like it works

Prisoner:

Spoiler

Returning to his own cell doesn't help at all. It's an impossible puzzle.

nah, Brunson's solution makes sense

Spoiler

as long as he returns to his cell after he murders his first inmate

 

[NateG]

The pope has one but doesn't use it
Nuns don't need one
Your father has one but your mother uses it
Arnold Schwarzenegger has a big one
Michael J Fox has a small one.
What is it?

 

[Cyrus C.]

The pope has one but doesn't use it
Nuns don't need it
Your father has one but your mother use it
Arnold Schwarzenegger has a big one
Michale J Fox has a small one.
What is it?

Spoiler

Last Name

 

[dannyz0r]

Spoiler

penisz0rr0r0r