Rubik's Clock is probably one of the easiest puzzles to solve (once you know how to do it, of course). The maximum number of moves is only 18! (That's eighteen, not eighteen-factorial).
There are two faces on a Rubik's Clock, and you must solve the first one before solving the second one. I call one the MIDNIGHT face (the side with the dark background) and the other the NOON face (the lighter one). You solve one face before solving the second one.
Solve the MIDNIGHT face:
1. Press all 4 of the yellow buttons up (towards you). Push the bottom 2 buttons down (away from you). Turn the upper black gears until the center dial matches the bottom dial.
2. Rotate the puzzle 90 degrees counter-clockwise and repeat step 1.
3. Rotate the puzzle 90 degrees counter-clockwise and repeat step 1.
4. Rotate the puzzle 90 degrees counter-clockwise and repeat step 1.
5. Press all the yellow buttons up; then push ONLY the bottom-left button down. Turn the upper black gears until the center dial matches the lower-left dial.
6. Rotate the puzzle 90 degrees counter-clockwise, and repeat step 5.
7. Rotate the puzzle 90 degrees counter-clockwise, and repeat step 5.
8. Rotate the puzzle 90 degrees counter-clockwise, and repeat step 5.
9. Press all the yellow buttons up. Turn the upper black gears until all the dials read 12 o'clock.
Flip the puzzle to the other side and now solve the NOON face:
10. Press all 4 of the yellow buttons up. Push the bottom 2 buttons down. Turn the upper black gears until the center dial matches the bottom dial.
11. Rotate the puzzle 90 degrees counter-clockwise and repeat step 10.
12. Rotate the puzzle 90 degrees counter-clockwise and repeat step 10.
13. Rotate the puzzle 90 degrees counter-clockwise and repeat step 10.
14. Press all the yellow buttons up; then push ONLY the bottom-left button down. Turn the upper gears until the center dial matches the lower-left dial.
15. Rotate the puzzle 90 degrees counter-clockwise and repeat step 14.
16. Rotate the puzzle 90 degrees counter-clockwise and repeat step 14.
17. Rotate the puzzle 90 degrees counter-clockwise and repeat step 14.
18. Press all the yellow buttons up. Turn the upper black gears until all the dials read 12 o'clock.
You have just solved Rubik's Clock.
FOR YOU EXPERTS:
It really doesn't matter if you solve the MIDNIGHT face first or the NOON face first. It also isn't mandatory that you "rotate the puzzle COUNTER-clockwise" each time; you can also rotate it CLOCKWISE each time, but which ever way you start to rotate it, you must continue that direction until you solve one face of the puzzle. I restricted the rules a little bit, only so they would not seem so vague. I remember a long time ago (1968) when they would actually put "L" and "R" on stereo speakers, because it was easier to say, "connect the LEFT wire to the LEFT speaker" than it was to go on with paragraphs of information explaining why it didn't matter at all. Other experts will also note that you can skip moves 6 through 9, down-sizing the number of moves from 18 to 14! (that's fourteen, not fourteen factorial).
CMcF