Question is a bit broad, but out of all the concepts under the financial engineering umbrella you're bound to explore the concept of ledgering eventually.

I've written a bit about it on my own co's product blog in an attempt to demystify some core concepts [1], [2], [3].

Still on ledgering and expanding into less mathematical and more applied concepts, I can also recommend a book called "The Accounting Game: basic accounting fresh from the lemonade stand" [4].

[1]: https://www.formance.com/blog/engineering/how-not-to-build-a... [2]: https://www.formance.com/blog/engineering/debits-and-credits... [3]: https://www.formance.com/blog/engineering/ledgering-all-the-... [4]: https://books.google.com/books/about/The_Accounting_Game.htm...