Find That Book

Hello, kind friends!

I am looking for a book that I read in hardcopy in my childhood (aka, the early 1990's) which was probably written 1990's or earlier. I have no recollections of the cover or the age of the book at the time.

Setting: American revolutionary war and preceding years, I think in New England.

Genre: historical fiction - probably aimed at older children, I think, but it might have just been from an older style of polite writing that did not mention sex or upsetting things in literature. (I read a lot of things as a child that I was probably not supposed to have read. :)

Main character: a young man who we follow from a poor childhood to adulthood. He's educated in a public (I think) single room schoolhouse with a single teacher. He's a mathematics and accounting genius from an early age, and at one point I believe there's a conflict with his schoolmaster who does not believe a student as dumb as him could be working out complicated mathematical problems without being instructed in how to do it. (He's not particularly un-intelligent, but he's Very Gifted in math and not much interested in other elements of education, and the character might be read as autistic to modern readers.)

Detailed scenes:
- conflict with his school master over math, but the boy's mathematical talents are later recognized and he's trained (apprenticed?) to someone in trade involving sailing ships or a port. The school room uses slate and, I think, lead pencils to write on them rather than chalk?

-at one point, a mentor he admires gives him a book to study on mathematics (Maaaybe Isaac Newton's Principia Mathematica, not sure) and the boy is embarrassed bc he cannot read Latin, but when he confesses the mentor arranges for him to have lessons.

-scene on a ship in a battle where he has to hide in the gunpowder room and calmly reads a book until the battle is over, causing people to exclaim that, of course, he'd be reading completely calmly in the powder room of a ship under fire, of course. The ship might be smuggling goods, not sure.

-There's a scene when he's an adult where, at a dinner party, his host asks him to solve a complicated mathematical question regarding compound interest over time bc the host would like to make sure that he has not been cheated by a bank or business partner. The host lays the details out, but says, Don't worry about solving it now, enjoy your tea, I'll give you some time with it later. But the main character thinks about it and comes back with a detailed answer without using any writing materials in a very short amount of time.

-This was a book I read on my own, from my school or classroom library, not something that was assigned