Well, I know what it is not. It is not the expansion of Avagadros number, nor the expansion of the decimal in any other constants I could think of. The sum of the digits is 117, which is not helpful. 117C=242.6 F. 117K=72.7 miles. 117 is not prime. The 31 digit number is divisible by 3.
31 digits does not lend itself to any particular groupings I am familiar with.
Converting each number to a corresponding letter in the alphabet (English) leaves nonsense.
I converted each number to its binary equivalent, but that did not prove helpful.
It is possible I have a mistake in the list, but even if I don't I am at a bit of a loss.
I did not have any trouble with the sides of a square pyramid. I did have to look up the C programming item. I never heard of an international draughts board so I had to look that up also.
At this point I am just going to leave it as my better half says I have wasted enough time on it.
Cheers

Al, my plan was to post the solution each time on a Thursday. I'm curious what you mean by this 'interpretation'. Maybe you ARE a giant spoiler, Al. No, you aren't of course, but in this case, I'm frightened of what to expect. So what about your revelation on Tuesday?

Adri
PS I hope 'spoiler' doesn't have a huge negative connotation in your part of the world. In any case, Merriam-Webster says:

1 a: one that /spoils/
  b: one (such as a political candidate) having little or no chance of winning but capable of depriving a rival of success
2 a: a long narrow plate along the upper surface of an airplane wing that may be raised for reducing lift and increasing drag → see /airplane illustration/
  b: an air deflector on an automobile to reduce the tendency to lift off the road at high speeds
3: information about the plot of a motion picture or TV program that can /spoil/ a viewer's sense of surprise or suspense
  also : a person who discloses such information

Alright, I meant 'a person who discloses such information' on a regular basis. And what if you did? Then you're a spoiler, I guess.

Adri,

At risk of giving the answer away, I'd observe that you need super power(s) to get there :-)

I think Sgt. Joe gave up on trying to understand the big number and, sadly, I don't see evidence that anyone else has had a go at it... Pity, as it was interesting (as always!)...

Cheers - Al.

P.S. By the way - re "spoilers" in yesterday's messages; despite the hours I keep(!), I'm in that country that left the EU a little while back :-( -- spoilers here usually refer to [written or spoken] items giving away plot lines, sports results, quiz answers or whatever... So one of the Merriam-Webster definitions was fair enough, the other usages are [I believe] less common...

But then I don't know where you went wrong, Sgt.Joe. So all that is left for you is to post all your answers, or at least those that you don't trust. Or find the hidden hint that was posted by Al.

Adri
PS 100% superb, Al!

Sgt. Joe,

14's wrong :-) -- I think that's Beryllium, not Helium?

Cheers - Al.