What is this tile-based game?
It sounds like you have yourself a Rummikub set, but with the blue and yellow sets missing their 12s and 13s. The indented circles are there mainly for the benefit of distinguishing the 6 and the 9 from each other. The racks are used for resting your unplayed tiles on - played tiles are placed on the table between the players.



The components of Rummikub


Numbered tiles coming in four colours: generally red, black, blue and yellow.
Each colour has two sets of tiles numbered from 1 to 13.
Two jokers. Normally these are black and red, and represented by a smiling face.
Four racks, since it's a game for up to four players.


All in all, you should have 106 tiles: 104 numbered, and two jokers.

That said, if you do have 104 tiles, you should only be missing two tiles, not eight! Have you counted correctly? Try laying them out and checking.