124) 이든지: it is used after the interrogatives such as 언제, 누구

, 어디, 무엇,얼마 to express either options do not matter. e.g. 무엇이든지

124-1)든지: it is used behind the noun that ends in vowels. e.g. 어디든지

e.g.
언제든지 오셔도 돼요(you may come anytime)

필요한 것이 있으면 무엇이든지 말씀하세요(if you need anything, let me know regardless of what it is)

우리 학교 학생이면 누구든지 이용할 수 있어요?(can any of the student from our school use it?)

***
It may be used as 이든지 이든지 form with nouns.

e.g.
1층이든지 2층이든지 모두 괜찮아요.
샌드위치든지 김밥이든지 마음대로 먹어

Q.
Choose the right one

1.보고 싶으면 얼마(이든지, 든지) 봐도 돼.

2.편한 옷이면 어떤 옷(이든지, 든지) 좋습니다.

3.커피(이든지, 든지) 녹차(이든지, 든지)아무거나 괜찮아요.

4.라면(이든지, 든지) 김밥(이든지, 든지) 다괜찮아요.