Which is correct?

1. It's quite a long book. There are 450 page / 450 pages.

2. I didn't have any change. I only had a twenty-pound / twenty pounds note.

3. I looked down and there were two ten-pound / ten pounds notes on the ground.

4. At work in the morning I usually have a 15-minute / 15 minutes break for coffee.

5. There are 60-minute / 60 minutes in an hour.

6. It's only a two-hour / two hours flight from London to Madrid.

7. My office is on the tenth floor of a twelve-storey / twelve storeys building.

8. I work five-day / five days a week. Saturday and Sunday are free.

9. Five-star / Five stars hotels are the most expensive.

10. Sam's daughter is six-year-old / six years old.

11. The oldest building in the city is the 500-year-old / 500 years old castle.

12. Do you use the twelve-hour / twelve hours clock or the 24-hour clock?