The openings can be arranged as follows:

1, you need four rooms to live in nine rooms.

It takes eighteen rooms to live in a double room.

We all need two rooms that can accommodate 18 people.

A triple room needs twelve rooms.

It takes three rooms to live in twelve rooms.

6. It takes six rooms to live in a six-person room.

Extended data:

When solving a problem, according to the needs of solving a problem, divide the problem into limited situations that are not repeated or omitted, list them one by one, analyze and solve them, and finally solve the whole problem.

When solving problems by enumeration, you need to master the following three points.

(1) When listing, attention should be paid to the orderly listing, and it is not allowed to be listed in disorder.

(2) according to the meaning of the problem, according to the scope and various situations to consider, so as to avoid duplication and leakage.

(3) Eliminate unqualified cases and continuously narrow the list.