One of the running gags was that Goku was so stupid (or just oblivious to everything) that he was literally incapable of determining gender without grabbing someone's crotch.
He learns the maths when he was a kid training under the turtle hermit Master Roshi. Book learning was part of the overall training in the turtle school. It's just that he's never really been socialized and is basically purely innocent. Minus the 150 or so aliens he's killed with his bare hands of course.
*Puts on nerd glasses* Four year difference. They do not date or get married to each other. Although when Goku grows up (18 yes old) and Bulma sees him again for the first time since he was a 15 she thinks he's dead sexy.
Nah, she marries his super whiny rival Vegeta who has a gigantic forehead and receeding hairline, like 300 episodes later in the series, and they she turns into a lesbian.
What, really? Wasn't Vegeta some massive villian, how does that work out?
"Ohhhhh you're cute and all.... but he's going to murder everyone! I think I want to marry him!"
A number of characters from Dragonball and Dragonball Z when defeated by Goku turn into side characters who only exist to show how much stronger Goku is then everyone else.
Almost every major villain joins Goku for various bullshit reasons, the most ridiculous being "so I can make sure no-one else gets to kill him even though I am an inferior fighter to him in every single way despite being at least as strong as him when we first fought." Eventually there are so many side characters that it becomes increasingly hard to give a damn about most/all of them, especially the annoying as fuck children.