what is the difference between 번호 and 숫자?
When I use first term and when second and are they interchangeable?

Thank you in advance.

Question

what is the difference between 번호 and 숫자?
When I use first term and when second and are they interchangeable?

Thank you in advance.

Answer

They are not interchangeable.

번호 is used to mark items or list things.
ex) 1번 후보  candidate number one
ex) 1번 문     Gate 1
ex) 101번 방     Room 101

숫자 is a general term for a number. 숫자 can be big or small, and can be calculated. Similar to a figure.
ex) 숫자가 크다/작다      The number is big/small.
ex) 여러 숫자들이 많다   There are many different numbers.
ex) 숫자 계산                 calculation of numbers

수치 is a resulting number after measurement or calculation.
ex) 혈압수치  blood pressure

Answer

Literally, The word 숫자(數字) -- 수(數)의 자(字) -- refers to a digit, one of the written signs that present the numbers, and it is often used to show an amount or quantity. 
The word 번호(番號) refers to a number used to show the position of something in an ordered set or list. So, when talking about a phone number, we say "전화 번호", not "전화 숫자". When counting the number, we should say that"숫자를 세다", not that "번호를 세다".

Answer

thank you...