**is called**

*Lateral Thinking XIII*

*"The Missing Number"*Your task is to find

*the missing number*.

Here it is,

54 (117) 36

72 (154) 28

39 (513) 42

18 ( ? ) 71

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

Your task is to find

Here it is,

54 (117) 36

72 (154) 28

39 (513) 42

18 ( ? ) 71

My drawings thread [size=120]HolmesÂ´Drawings

*Amazing banner done by KaitoGirl, thank you very much! *

*Amazing banner done by KaitoGirl, thank you very much! *

- Sayumi
**Posts:**124

I'm kinda busy with tests and assignments at the moment, but I couldn't stop myself

[spoiler]add up the outer and inner numbers

54 (117) 36

5+6=11

4+3=7

same with:

72 28

7+8=15

2+2=4

154

and

39 42

3+2=5

9+4=13

513

so

18 71

1+1=2

8+7=15

215[/spoiler]

[spoiler]add up the outer and inner numbers

54 (117) 36

5+6=11

4+3=7

same with:

72 28

7+8=15

2+2=4

154

and

39 42

3+2=5

9+4=13

513

so

18 71

1+1=2

8+7=15

215[/spoiler]

"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."

Sherlock Holmes

Sherlock Holmes

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

Nice one Sayumi! Well, as expected

Oh, and btw, good luck with your exams and assingments.

Oh, and btw, good luck with your exams and assingments.

My drawings thread [size=120]HolmesÂ´Drawings

*Amazing banner done by KaitoGirl, thank you very much! *

*Amazing banner done by KaitoGirl, thank you very much! *

- ayw
- å®‰å¿ƒã
**Posts:**95

I needed quite a while to figure this one out... my LT thinking is getting rusty :-\ Thanks for continuing to post these riddles, Holmes!

Here are two more to keep the water boiling...

[tt]53 (73) 21

36 (45) 72

94 (68) 78

15 (??) 67[/tt]

`4678 (74) 3419`

3224 (39) 8962

1572 (21) 6421

9839 (??) 3031

*Edit* - hints:

Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·

A little hint for the upper one

Notice how the outer two numbers are always either both odd or both even.

And a little hint for the lower one

No arithmetic is required for this one

Here are two more to keep the water boiling...

[tt]53 (73) 21

36 (45) 72

94 (68) 78

15 (??) 67[/tt]

3224 (39) 8962

1572 (21) 6421

9839 (??) 3031

Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·Â·

A little hint for the upper one

Notice how the outer two numbers are always either both odd or both even.

And a little hint for the lower one

No arithmetic is required for this one

Last edited by ayw on March 22nd, 2009, 8:42 am, edited 1 time in total.

- Sayumi
**Posts:**124

Finally figured out the first one-took me ages... I had already noticed what you mentioned in your hint, I just didn't realise that it's significant...(can't believe it took me so long-it wasn't that hard!)

Here I go:

(53+21):2= 37 -> 73

(36+72):2= 54 -> 45

(94+78):2= 86 -> 68

(15+67):2= 41 -> 14

Still working on the second one...

Here I go:

(53+21):2= 37 -> 73

(36+72):2= 54 -> 45

(94+78):2= 86 -> 68

(15+67):2= 41 -> 14

Still working on the second one...

"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."

Sherlock Holmes

Sherlock Holmes

- ayw
- å®‰å¿ƒã
**Posts:**95

- Sayumi
**Posts:**124

Got it!!!!

Yay, this was fun! You made my day ayw!

Here it is!

it always is the only odd/even one

46**7**8 (74) 3**4**19

**3**224 (39) 8**9**62

157**2** (21) 642**1**

9**8**39 (80) 3**0**31

Yay, this was fun! You made my day ayw!

Here it is!

it always is the only odd/even one

46

157

9

Last edited by Sayumi on March 22nd, 2009, 6:02 pm, edited 1 time in total.

"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."

Sherlock Holmes

Sherlock Holmes

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

I hate this, not even spoilers can be put!!! >:( >:(

The first one:

You sum the two numbers, divide it by two and read it backwards, so the last one is ...

(15+67):2 = 41 --**14.**

The second one, it is either odd or even, so the last one is ...

9*8*39 -- 80 -- 3*0*31

Have to continue this thread or find a Lateral Thinking XIV ... mmm

The first one:

You sum the two numbers, divide it by two and read it backwards, so the last one is ...

(15+67):2 = 41 --

The second one, it is either odd or even, so the last one is ...

9

Have to continue this thread or find a Lateral Thinking XIV ... mmm

Last edited by Holmes on March 22nd, 2009, 8:10 pm, edited 1 time in total.

My drawings thread [size=120]HolmesÂ´Drawings

*Amazing banner done by KaitoGirl, thank you very much! *

*Amazing banner done by KaitoGirl, thank you very much! *

- ayw
- å®‰å¿ƒã
**Posts:**95

Sayumi, Holmes, clean sweep!

Yeah, too bad we can't use spoilers for the moment... I guess they'll have it fixed soon. Most other things seem to work, though.

Yeah, too bad we can't use spoilers for the moment... I guess they'll have it fixed soon. Most other things seem to work, though.

- Sayumi
**Posts:**124

Okay... my turn...

9798 (30) 6495

8531 (22) 9742

3758 (46) 3752

7328 ( ) 1217

and

11235 (9) 121416

2468 (5) 36912

000 (4) 888

876 ( ) 19232931

modified version:

1 1 2 3 5... (9) ...12 14 16...

...2 4 6 8... (5) ...3 6 9 12...

...0 0 0... (4) ...8 8 8...

...8 7 6... ( ) ...19 23 29 31...

9798 (30) 6495

8531 (22) 9742

3758 (46) 3752

7328 ( ) 1217

and

11235 (9) 121416

2468 (5) 36912

000 (4) 888

876 ( ) 19232931

modified version:

1 1 2 3 5... (9) ...12 14 16...

...2 4 6 8... (5) ...3 6 9 12...

...0 0 0... (4) ...8 8 8...

...8 7 6... ( ) ...19 23 29 31...

Last edited by Sayumi on March 24th, 2009, 1:14 pm, edited 1 time in total.

Sherlock Holmes

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

Number 2 cuaght my curiousity:

This is what I find interesting:

112358 -- Fibonacci sequence

121416 -- 12+2=14 + 2= 16 so 12,14,16

2468 -- same as 121416

36912 -- all multiples of 3= 3,6,9,12

000 and 888 -- 3 identical numbers

876 -- numbers descending= 8,7,6

19232931 -- a sequence of prime numbers= 19,23,29,31 in order

Maybe this means nothing, maybe this is a hint, maybe I have to think a little more and IÂ´ll get it, or maybe this is just a coincidence of Destiny.

EDIT: I think this is the answer, 3minutes after I posted

I think all this sequences tell you that itÂ´s all related, so maybe the numbers in the middle are also related. The top number is 9, followed by 5 and 4, 5+4= 9. So maybe the last number is x+4=5, x=1, so the last number is 1.

This is what I find interesting:

112358 -- Fibonacci sequence

121416 -- 12+2=14 + 2= 16 so 12,14,16

2468 -- same as 121416

36912 -- all multiples of 3= 3,6,9,12

000 and 888 -- 3 identical numbers

876 -- numbers descending= 8,7,6

19232931 -- a sequence of prime numbers= 19,23,29,31 in order

Maybe this means nothing, maybe this is a hint, maybe I have to think a little more and IÂ´ll get it, or maybe this is just a coincidence of Destiny.

EDIT: I think this is the answer, 3minutes after I posted

I think all this sequences tell you that itÂ´s all related, so maybe the numbers in the middle are also related. The top number is 9, followed by 5 and 4, 5+4= 9. So maybe the last number is x+4=5, x=1, so the last number is 1.

Last edited by Holmes on March 24th, 2009, 11:40 am, edited 1 time in total.

*Amazing banner done by KaitoGirl, thank you very much! *

- Sayumi
**Posts:**124

@Holmes:

First part:

Yep, sequences are very important!

Second part:

Not the one I meant - it's not distinct enough... but a good idea!

First part:

Yep, sequences are very important!

Second part:

Not the one I meant - it's not distinct enough... but a good idea!

Sherlock Holmes

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

I think this might do it, if it doesnÂ´t, I would have found 2 different answers for this one Sayumi, haha

HereÂ´s my answer,

First I tried to think the relationship between the numbers in the middle with the one at their side. So, 11235 (9) 121416,

if you lin this two and you sum, you get 233766, this made me think:" One number, two 3Â´s, one number, two 6Â´s, so maybe one number and two 9Â´s. 9 is the middle number.

After this 2468 (5) 36912,

you also line up and you sum the digits: 2+3, 4+6, 6+9, 8+12 and you get 5,10,15,20, multiples of 5 in order. 5 is the midle number.

Finally 000 (4) 888,

4x222=888. 4 is the middle number.

This cost me a lot, a relationship between 876 and 19232931, WTF!!! i made the same as the others, line up and sum, but ... terible. After that I continued with the general idea, and suddenly I thought: "Maybe I have to sum all the digits: 8+7+6+1+9+2+3+2+9+3+1= 51

51=17x3 -- 17 is the privious prime number 17,19,23 so.

because of all this I say that 3 is the last number.

I hope this is ok, if it is, I have to congratulate you for thinking this one that would gave most people a headache for a month(IÂ´m included and this reminds me Lateral Thinking V, the one of the people, the dogs and the boat) After you say yes or no, IÂ´ll think number 1. Would like to see aym thinking this one. Thanks again!

HereÂ´s my answer,

First I tried to think the relationship between the numbers in the middle with the one at their side. So, 11235 (9) 121416,

if you lin this two and you sum, you get 233766, this made me think:" One number, two 3Â´s, one number, two 6Â´s, so maybe one number and two 9Â´s. 9 is the middle number.

After this 2468 (5) 36912,

you also line up and you sum the digits: 2+3, 4+6, 6+9, 8+12 and you get 5,10,15,20, multiples of 5 in order. 5 is the midle number.

Finally 000 (4) 888,

4x222=888. 4 is the middle number.

This cost me a lot, a relationship between 876 and 19232931, WTF!!! i made the same as the others, line up and sum, but ... terible. After that I continued with the general idea, and suddenly I thought: "Maybe I have to sum all the digits: 8+7+6+1+9+2+3+2+9+3+1= 51

51=17x3 -- 17 is the privious prime number 17,19,23 so.

because of all this I say that 3 is the last number.

I hope this is ok, if it is, I have to congratulate you for thinking this one that would gave most people a headache for a month(IÂ´m included and this reminds me Lateral Thinking V, the one of the people, the dogs and the boat) After you say yes or no, IÂ´ll think number 1. Would like to see aym thinking this one. Thanks again!

Last edited by Holmes on March 24th, 2009, 12:34 pm, edited 1 time in total.

*Amazing banner done by KaitoGirl, thank you very much! *

- Sayumi
**Posts:**124

@Holmes

It's still not the one I meant though I totally love your answer ! The first answer was closer but the prime number part was right. I put up a modified version maybe that'll help to show what i'm looking for.... Hope you'll have another go at it. I'll send ayw a note to have a look at it as well

I guess there is more than one answer for it though-I just thought of this while being at school, so it's probably not flawless. But the answer is easier than what you came up with...

awww... I really miss the spoiler tags!

It's still not the one I meant though I totally love your answer ! The first answer was closer but the prime number part was right. I put up a modified version maybe that'll help to show what i'm looking for.... Hope you'll have another go at it. I'll send ayw a note to have a look at it as well

I guess there is more than one answer for it though-I just thought of this while being at school, so it's probably not flawless. But the answer is easier than what you came up with...

awww... I really miss the spoiler tags!

Sherlock Holmes

- Holmes
- Erabareshi Kodomotachi
**Posts:**1291

Although itÂ´s wrong I really like to think taht answer, IÂ´ll think about the modified one tomorrow at school: I have the the most boring subjects.

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