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I would like to know how to calculate the unique combinations in the following scenario.

There are 3 levels:

  1. Building
  2. Rooms in the building
  3. Objects in room

There are 15 buildings, 9 rooms and 9 objects in each room.

A user has to choose 1 building, 1 room in that building and 1 object in the room.

Thanks!

1 Answers 1

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Select one building $\dbinom{15}{1}$

Select one room $\dbinom{9}{1}$

Select one object $\dbinom{9}{1}$

so,

$\dbinom{15}{1}\dbinom{9}{1}\dbinom{9}{1}$ ways