number vs problem in Korean
번호vs문제

번호number
The word "number" means a numeral or a set of digits used to identify something. In Korean, 번호 often means a phone number, seat number, bus number, or student number. You use it when you ask for or tell the number of something in everyday life. At school, it can also mean your class number or student number.
When to use number
문제problem
문제 means a problem. In school, it often means a question or exercise in a workbook, homework, or a test. You can also use it for a difficulty in daily life, like a problem with a computer or a ticket.
When to use problemHow they differ
번호 is a number, like a student number, phone number, or the number of a test item. It does not mean the question or problem itself.