# Thread: Finding rules of number pyramids

1. ## Finding rules of number pyramids

Hello all, I have a problem with this number pyramids.

I have to find what number goes in ①.
And I need to know what rules have come up with such correct answers.

I would be very grateful if you could solve this problem.

2. ## Re: Finding rules of number pyramids

Where did this puzzle come from? I may be wrong, but I think there's a typo in it, perhaps two. First I believe the lower left number in the 4th pyramid should be 10, not 1. This would make the pattern for the lower left numbers 1, 3, 6, 10, 15, which is a pretty simple sequence. With that change the center number of each pyramid is 2 times the sum of the three outer numbers, but with one exception: following this rule the middle number of the second pyramid should be 18, not 1. And the missing number is then 2(9+15+81) = 210. I realize that the probability of having two typos in this puzzle is small, but it's something to consider.

3. ## Re: Finding rules of number pyramids

I don't have the solution, but noticed that the top triangles are a logic suite, same for bottom right ones.

Top is +2 for each pyramid, bottom right is x3.
Bottom left doesn't seem to have a similar logic, so I think it's key to finding the solution. I thought it could be a modulo or something and would work with central section? Not quite sure...

4. ## Re: Finding rules of number pyramids

Originally Posted by ChipB
First I believe the lower left number in the 4th pyramid should be 10, not 1.
...the middle number of the second pyramid should be 18, not 1.
AGREE!
Looks like last digits (0 and 8) were accidentally dropped...