I thought that it was considered rude to say as if we know that someone wants something. So what would be the proper way in Japanese to ask if they want us to do something? Like "Would you like me to tell you my number?"
Below is what I have in mind, please correct me if I'm wrong so I can learn from it...:
This is wrong since we cannot use たい for other people...
This is wrong since we cannot use 欲しい for other people too...
I'm not sure which one is correct or if both are wrong. But even if it is correct, it would also mean somewhat like "Teacher, is it okay if I tell you my number?" and a bit different to "Teacher, would you like me to tell you my number?"...
I'm not completely sure, but this should means "Teacher, should I tell you my number?". Although it has a difference nuance from "Would you want me to tell you something?" but it serves a similar purpose. Is this the correct one?
Additional for information purpose. Based on Oal's comment, it seems it's safe to use たほうがいい. as in