How Far is a Light-Year?

A light-year is a unit of length used by astronomers to measure interstellar distance (the distance between stars). A light-year is defined as the distance that light will travel in a year. If the speed of light is 186,000 miles per second (300,000 km per second), then calculate the distance that light will travel in one year. Express your answer in miles per year. [Note: Cancel similar units above and below the dividing line. This process is known as "dimensional analysis."]

Solution:

186,000 mi/sec x 60 sec/min x 60 min/hr x 24 hr/day x 365 days/yr