riddle from facebook

[Tennentslager]

1+4=5

2+5=12

3+6=21

8+11=?

 

 

[daiking]

52?

 

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edit: doh, using the same series I've identified I should have said 96.

8 + 11*4 = 52 doesnt follow. When I know it should be 4x + x^2

Edited June 1, 2016 by daiking

[Bornagain]

40.

[Guest Alphonsox]

96

[Bornagain]

c'mon guys, it's not as complicated as you are thinking......

[Tennentslager]

96 for me...

[Stones]

40

[ProDave]

Can someone post some reasoning as I can't make sense of it. All I see is incorrect sums so you are asking me to guess the answer of the last incorrect sum?

I started thinking ah, they must be adding up in base 6, but you can't have more than a number 5 then can you so that only works for the first 2.

[Crofter]

96 from me too.

It's not as hard as you think, Dave!

[ProDave]

Give me a clue as I am obviously over thiking it.

[reddal]

I dont think there is a single right answer - there are many patterns - several give 96, one gives 40, another 201. You could probably construct any answer with a complex enough rule. If the question becomes which pattern is the most elegant? Well its a bit subjective...

[Calvinmiddle]

96

[Mikey_1980]

40

1+4=5

2+5=7+5 from the Previos Answer =12

3+6=9+12 from the previous answer =21

8+11=19+21 from the previous answer = 40

Edited June 1, 2016 by Mikey_1980

[Ferdinand]

96.

RHS = First Number + (First Number * Second Number)

or

C = A(1+B)

Edited June 1, 2016 by Ferdinand

[Redoctober]

  On 01/06/2016 at 08:12, Mikey_1980 said:

40

1+4=5

2+5=7+5 from the Previos Answer =12

3+6=9+12 from the previous answer =21

8+11=19+21 from the previous answer = 40

Expand  

Spoiler ! 40 for me and thankfully got there before scrolling down - a nice little teaser from after a long and wet commute

[Construction Channel]

Im sticking with 96. 

if you were to go down the road of getting 40, surely you would need to fill in the rest of the sequence

4+7=11+21=32

5+8...... and so on so the answer wouldn't be 40 anyway

[ProDave]

  On 01/06/2016 at 08:12, Mikey_1980 said:

40

1+4=5

2+5=7+5 from the Previos Answer =12

3+6=9+12 from the previous answer =21

8+11=19+21 from the previous answer = 40

Expand  

But on that logic, should you have not done the whole sequence including the sums not shown, 4+7, 5+8, 6+9, and 7+10 then finally adding the total to the 8+11 sum?

[Construction Channel]

1	4	5
2	5	12
3	6	21
4	7	32
5	8	45
6	9	60
7	10	77
8	11	96
9	12	117
10	13	140
11	14	165
12	15	192
13	16	221
14	17	252
15	18	285
16	19	320

 

Guess what it comes out as anyway

although i should say i got there the first time by (8x11)+8=96

 

[Nickfromwales]

I got 96 but thought I'd left it too long to get any credibility. 

Ed, step away from the calculator. 

[Construction Channel]

next question is can someone elegantly explain why it works both ways?

(A*B)+a=x   and  A+B+(previous x)=x

 

not exactly similar

????

 

[SteamyTea]

Not looked at anyone else's answers, but have seen this before.

Change the + to * and add one to the second number.

so 8+11 = 8*(11+1) =  8*12 = 96

Edited June 3, 2016 by SteamyTea
I forgot BODMAS