So, my 5-year-old nephew is obsessed with huge numbers, especially named numbers such as googol, duodecillion, and centillion. The other day I spent some time reciting these numbers to him, and trying (and failing) to describe them. What I need are some cool facts about these numbers, such as "there are 1 quadrillion cat hairs in the world", or "there are not enough stars in the universe to fill one googol".

Besides math, his main interests are super-heroes and, apparently, cars.

I'm not a math or physics guy, so hopefully you guys can help me cheat :P

For a very, very long time, I've had a strange but persistent envy of people who have good "logical" thinking skills or who can do math well. I wish that I was the type of person who could play chess to even a passable degree, as I'm convinced a toddler could beat me. But most of all, I wish I could learn something like calculus, which has held a strange allure for me even as a young kid. But I was failing math as early as the fifth grade, and do not remember even an iota of information about geometry or trigonometry. Ultimately, I dropped out of school altogether.

A year or so ago I started in the "pre-K" mathematics category of Khan Academy, because I had such a low opinion of my own abilities. Sure enough, I breezed by it, but even found some parts of the second or third grade curriculum difficult. It's like I was born completely without numerical ability, but I don't want to go so far as to say I have something like dyscalculia, as I at least read analog clocks and musical notation on a daily basis, and have no problem discerning if a number is bigger or smaller than another. I'm also decidedly not aphantastic; quite the opposite. Something I do have is an extreme distrust or even hatred of my own critical thinking abilities. If I mess up simple arithmetic, I'll beat myself up mentally for being "stupid," or an "idiot," and so on for way too long. It's a habit I learned early. Complicating matters is that I'm in my mid-twenties, so my neuroplasticity is probably not great. In fact, one of my deepest fears is that it's too late for me to learn any new subject to a competent degree.

This might be a ridiculous thing to say, but I'm hoping someone can reassure me that it's possible to learn math as an adult, even for a "hopeless" case like me. If you've been in a similar situation and have found particular resources helpful, I'd really like to see them. Khan Academy wasn't really my thing, but if it's more or less the best option for someone like me, I'll try it again.

I'm creating the concept for a story called The Little Differences. It's about an accountant that, one day, out of the blue, notices that a certain calculation is producing a slightly wrong result. Barely noticeable, nothing world-changing,

He runs it on the computer, tries different software, a physical calculator... everything gives a result that's a little off. When he checks on paper himself, he gets the correct result. But, to his surprise, everyone else tells him that he's the one that's off, and that the incorrect result is actually perfectly sound.

I need something that makes sense, mathematically. The weird result must be something that really is wrong, and not just something that programs sometimes get wrong (I don't want it to be explained at all... I mean, the reason why it is occurring must not be something easily reducible to some well-known malfunction). But it must also be minor enough for someone to miss, something that wouldn't really cause much trouble in the real world (is that possible? IDK).

Lastly: it must be something that I'm able to explain (on some level) to a non-math reader.

So, Tildes math wizzes, what you suggest? :D

I am looking for practical ways to prove the Earth is round using materials accessible to the average person. I have zero interest in disproving Flat Earth folks.

I am inspired by Dan Olson's (Folding Ideas) excellent video where he is able to do this measuring the curvature of a lake near his home that has a very specific geography that lends itself to this sort of experiment. I've seen all sorts of ways to prove this measuring shadows and poles, using gyroscopes, etc. and wanted to know if there are any practical guides for proving once and for all that the Earth is round for yourself relying on nothing more than experimentation.

What I'm not looking for:

• Math relying on flight times/charts
• Video/picture evidence
• Deductive proofs built on agreed upon premises
• Expensive tests
• Extremely time consuming projects
• Underwhelming results (relying on a probabilistic argument for a round Earth from the evidence.)

What I am looking for:

• Practical experiments
• Things I could potentially do without spending much money
• Tests that aren't largely comprised of accepting someone else's research
• Potentially math-heavy evidence
• Results that are strong and conclusive

I've thought of finding some easy to test version of Eratosthenes' proof using two poles. I've also thought about using a balloon and sending something to space like what is done in this Tom Scott video. Nothing seems well documented in such a way as for me to be able to follow it at home.

TL;DR: I think it would be a meaningful experience to have the power to prove the Earth is round by myself, for myself. I can only compare this desire to the desire a child with a telescope has when wishing to observe Saturn or Mars themselves for the first time. It's not to prove anything or to settle doubts, but for the personal value of independently observing this astronomical fact oneself.