# Find the missing domino

In my last school-class I did a logic-test with 48 exercises about finding the missing dominoes. I'm sure about 47, but this one broke my head, and I don't know yet the answer:

It is

3,6 since the sum of diagonally opposite squares sum up to 6.

So the picture is

• Wow! I didn't realized that... good eyes! – removed Mar 7 '16 at 21:27
• Why does the 3 go on the inside and the 6 on the outside? Or are there two correct solutions? – Paul Evans Mar 7 '16 at 21:34
• The inner squares are in correspondence, and the outer squares are in correspondence. – Improve Mar 7 '16 at 21:35
• Of course, I dont intend to claim that it is the only correct solution, but it is one that seemed natural enough to me. – Improve Mar 7 '16 at 21:48
• @Improve I think the only solid answer is that it's not a very good logic test! But I can see why yours is probably the "correct" answer. – Paul Evans Mar 7 '16 at 21:52

It could be anything but let's guess:

You have a total of 15 on the inside circle and 12 on the outside circle.
So say they have to add up to the same number for some obscure reason.
Remember it could be anything - so let's take a wild pot shot at:
We have 2 dominoes that total 8 and two that total 4 and one that totals 3.
So for symmetry, lets say the missing domino has to total 3.
So it's blank on the inside circle and 3 on the outside circle.
For a total of 15 on both the inside and outside circle and two matching sums all around.

2,5 Two dots are added to each square on the domino directly opposite.