Oral route. Many drugs can be administered orally as liquids, capsules, tablets, or chewable tablets. Because the oral route is the most convenient and usually the safest and least expensive, it is the one most often used. However, it has limitations because of the way a drug typically moves through the digestive tract.
Measuring Distances to Stars. Astronomers use several techniques for discovering how far away an object is. The first is called trigonometric parallax and is based on geometry, but it is only good for up to about 500 light-years.
The nearest star is about 24 trillion miles away. That is 24,000,000,000,000 miles. If a scientist wanted to do a math problem with that huge number it would be very difficult. To make this number smaller we use something called light years.