So Bitcoin has 21,000,000.00000000 in existence. How does someone determine how many zeros are placed behind it? Could someone make an asset that has 1 coin but 1.910980182309824791827981240912094109249129837 in total token supply ?
It has simply been "determined" that way. There is not really any technical reason other than 10^8 being a somewhat "convenient" number.
See
https://bitcoin.stackexchange.com/questions/31933/why-is-bitcoin-defined-as-having-8-decimal-placesWhich points to this answer:
I remember this discussion, actually.
Finney, Satoshi, and I discussed how divisible a Bitcoin ought to be. Satoshi had already more or less decided on a 50-coin per block payout with halving every so often to add up to a 21M coin supply. Finney made the point that people should never need any currency division smaller than a US penny, and then somebody (I forget who) consulted some oracle somewhere like maybe Wikipedia and figured out what the entire world's M1 money supply at that time was.
We debated for a while about which measure of money Bitcoin most closely approximated; but M2, M3, and so on are all for debt-based currencies, so I agreed with Finney that M1 was probably the best measure.
21Million, times 10^8 subdivisions, meant that even if the whole word's money supply were replaced by the 21 million bitcoins the smallest unit (we weren't calling them Satoshis yet) would still be worth a bit less than a penny, so no matter what happened -- even if the entire economy of planet earth were measured in Bitcoin -- it would never inconvenience people by being too large a unit for convenience.
To quote Arturo's second part of his answer.
I'm not entirely sure if this was known at the time of implementation though.
So Bitcoin has 21,000,000.00000000 in existence. How does someone determine how many zeros are placed behind it? Could someone make an asset that has 1 coin but 1.910980182309824791827981240912094109249129837 in total token supply ?
Yes?