1) When you are designing a buliding.
-You need to know how many of a certain supply that you will need to finish the project. (eg. how much wood)
2) When painting a room.
-You need to know how much paint to buy based on how much it covers.
3) When (and if) you ever sew bed sheets.
-You need to know how much of the bed the sheets will cover.
4) When you are moving.
-You need to know how much space you will have for your furniture.
5) When you wrap a present.
-You need to know how much wrapping paper you will need based on the size of the present.
6) If you plan a wedding or other special event.
-You would need to know how much people and tables/chairs will fit into the rooms.
7) If you ever need to make ear warmers for an elephant.
-You would have to know the surface area of the elephants ears in order to make a hat.
8) If you are a clothing designer.
-You would need to know the size of the person to be able to make clothes that fit them perfectly.
9) If you decided to be a carpenter.
-You would need to know the surface area of people's floors in order to make carpets.
10) If you buy a door.
-You would need to know the measurements of the door frame so that the door would fit.
11) If you are writing an essay by hand.
-You would need to know how many pages that you would need based on how much you want to write.
12) If you ever decide to become anyone that teaches surface area.
-Well, obviously you need to know it to teach it!
13) If you are building out your backyard.
-You would need to know if you have enough space for a deck and pool.
14) When you are farming.
-You need to know if you have enough space for the amount of crops that you want, and if there is enough space for a certain type of crop that you may need more of.
15) When you are a real-estate agent.
-You would need to know if there is enough space for the amount of people that are going to live there.