Wah How to use Numbers as Adjectives.

We can make an adjective by linking number with singular noun.

200 + page
This is 200-page book. (This book has 200 pages.)

1000 + step 
It was a thousand-step ladder. (The ladder had 1,000 steps.)

five + minute
It's a five-minute walk from here. (It takes five minutes to walk there from here.)

Note: The noun must be singular.
It is nine pounds dog.  It is nine-pound dog.

• It was a ten-day job. (I work ten days.)
• I made a three-layer cake.
• This is a twelve-room house.
• It is a 4-door car.
• It was a 6-hour flight.
• This is a 3-hour lesson.

Look at the difference of these sentences.

• I saw a two-foot tree. (There was only one tree that was 2 feet height.)
• I saw a two foot-tree. (There were two of them and they were a foot height.)

I took a thousand-mile road trip.