In one of the building blocks at Oakland High there are 5 classes. Each class uses 2 whiteboards each and each whiteboard needs about 20ml of ink for a day's use. If ink costs 50 cents per ml, how much (in dollars) would it cost to use the boards for one day? Let's be accurate as possible.
Each ml of ink costs 50 cents so 20 ml costs 20 * 50 = 1000 cents. There are 2 whiteboards in each class so each class needs 2 * 1000 cents = 2000 cents. There are five classes in the block so they all need 5 * 1 * 2000 cents = 10000 cents. 100 cents make a dollar so 10000 cents make 10000 / 100 = $100.
The answer: 100.