If the only things you were allowed were paper and pencil, say you were creating bitcoin in the 15th century, how would you do it? I ask because I'm trying to get a better understanding of how bitcoin works, and i think this would help a lot.
https://www.youtube.com/watch?v=y3dqhixzGVoYou will like this video. That is all that happens in the hashings but tons of times per second, which is what makes BTC so secure.