Question mark is 4.
o Red circle is sum of left lower and upper numbers in each triangle multiplied by right lower number.
o 1st triangle: 3×4 + 3×8 = 36
o 2nd triangle: 4×8 + 4×5 = 52
o 3rd triangle: 30 – (3×6)/3 =12. Missing number is 12/3 = 4.

I can find two algorithms, with the same outcome:
1. Multiply the bottom right number with the other two, sum the products and you get the middle number. Solution: 4
Or
2. Multiply the smallest number among the corner numbers with the other two, sum the products and you get the middle number. Solution (a little harder): 4.

In each of the former triangles the centre circle is the result of adding the top number and the lower left number and multiplying the sun by the lower right number.
In the first two:
(8 + 4) x 3 = 36
(5 + 8) x 4 = 52
So in the third triangle
( 6 + ? ) x 3 = 30
? = 10

marioberges| Profile October 25th, 2009 - 10:13 pmEvery triangle has three numbers besides the center one. I will call them x, y, z for (top, left and right) and c for the center one.

The formula is:

c = x * z + y * z

For example, in the first triangle:

36 = 4 * 3 + 8 *3

In the last triangle, we need to solve for y, so we have:

30 = 6 * 3 + y * 3

y = (30 – 6 * 3) / 3

y = 4

Obiwan| Profile October 25th, 2009 - 11:19 pmQuestion mark is 4.

o Red circle is sum of left lower and upper numbers in each triangle multiplied by right lower number.

o 1st triangle: 3×4 + 3×8 = 36

o 2nd triangle: 4×8 + 4×5 = 52

o 3rd triangle: 30 – (3×6)/3 =12. Missing number is 12/3 = 4.

Obiwan| Profile October 25th, 2009 - 11:21 pmOops–left out brackets!

[30-(3×6]/3 = 4

goofymushu| Profile October 26th, 2009 - 1:12 ami think its 4

Reka| Profile October 26th, 2009 - 1:17 amIt’s a four!

kitchen| Profile October 26th, 2009 - 1:56 am4 (30 = 3*(4+6))

Falwan| Profile October 26th, 2009 - 2:42 ampattern :

(8+4)(3) = 36

(5+8)(4) = 52

(6+?)(3) = 30 —-> ?=4

bigbossSNK| Profile October 26th, 2009 - 3:29 amI can find two algorithms, with the same outcome:

1. Multiply the bottom right number with the other two, sum the products and you get the middle number. Solution: 4

Or

2. Multiply the smallest number among the corner numbers with the other two, sum the products and you get the middle number. Solution (a little harder): 4.

joe| Profile October 26th, 2009 - 4:37 amThe question mark should be a 4.

In each of the former triangles the centre circle is the result of adding the top number and the lower left number and multiplying the sun by the lower right number.

In the first two:

(8 + 4) x 3 = 36

(5 + 8) x 4 = 52

So in the third triangle

( 6 + ? ) x 3 = 30

? = 10

joe| Profile October 26th, 2009 - 4:37 amSorry that should be ? = 4 of course

hex| PUZZLE MASTER | Profile October 26th, 2009 - 5:09 am4

(8+4)x3=36

(5+8)x4=52

(6+4)x3=30

Mashplum| PUZZLE MASTER | Profile October 26th, 2009 - 7:38 am4

(top + left) * right = center

suineg| PUZZLE MASTER | Profile October 26th, 2009 - 8:09 amcool I think one answer could be this:

first triangle: (8+4)*3= 36

second triangle: (5+8)*4= 52

third triangle: (6+4)*3= 30

so the answer is 4

Sally| Profile October 26th, 2009 - 8:51 am4

mimi112| Profile October 26th, 2009 - 9:44 am4

Shawn| PUZZLE GRANDMASTER | Profile October 26th, 2009 - 10:56 am4

moyes| Profile October 26th, 2009 - 12:00 pmIs the answer 4.

6×3= 18, 3×4= 12, 18+12 =30

_______________________

Triangel 1:

8×3=24, 3×4= 12, 24+12=36

____________________

Triangel 2:

8×4=32, 4×5= 20, 32+20= 52

Mr DeJerk| Profile October 26th, 2009 - 2:50 pm4

nattlebattle| Profile October 26th, 2009 - 6:30 pm4!

(Top + Bottom Left) * (Bottom Right) = Middle

(8 + 4) * (3) = 36

(5 + 8) * (4) = 52

(6 + 4) * (3) = 30

Jimmy Anders| PUZZLE MASTER | Profile October 26th, 2009 - 6:44 pmIf the pattern is that the middle number (red) is the sum of the two numbers on the left multiplied by the third number, then the answer is 4.

[6 + 4] * 3 = 30

Hercules| Profile October 26th, 2009 - 9:54 pmthe answer is 4

36 divide by 3 is 12…8 and 4 are 12

52 divided by 4 is 13…5 and 8 are 13

30 divided by 3 is 10…6 and ‘4’ are 10

Oneiric| Profile October 26th, 2009 - 11:16 pmI’d say 4.

Let’s call the top number T, the bottom left number BL, the bottom right number BR and the center number C.

C = T * BR + BL * BR

Figure 1: 36 = 8 * 3 + 4 * 3 (24 + 12)

Figure 2: 52 = 5 * 4 + 8 * 4 (20 + 32)

Figure 3: 30 = 6 * 3 + BL * 3

30 = 18 + BL * 3

Previous minus 18: 12 = BL * 3

Previous divided by 3: 4 = BL

Shofnite| Profile October 27th, 2009 - 4:44 am(8+4) * 3 = 36

(5+8) * 4 = 52

(6+x) * 3 = 30

x = 4

Blusummers13| Profile October 27th, 2009 - 11:27 amThe answer is 4.

8*3+4*3=36

5*4+8*4=52

6*3+x*3=30 x=4

ubthecat| Profile October 27th, 2009 - 11:34 pm4

ohjirochan| Profile October 28th, 2009 - 4:01 am4

kxvinu| Profile October 28th, 2009 - 4:31 am4

RK| Founder | Profile November 3rd, 2009 - 11:37 pmvery good- 4 is the answer

10dulkar| Profile March 3rd, 2010 - 1:22 pmOh did anyone mention 4 yet? LOL

kamiliuxs| Profile August 12th, 2010 - 8:27 am4