Here's a breakdown:

* Degrees: The Earth is divided into 360 degrees of longitude, starting at the Prime Meridian (0 degrees) and going east and west to 180 degrees.

* Minutes: Each degree is further divided into 60 minutes.

* Seconds: Each minute is then divided into 60 seconds.

Therefore, a complete circle of longitude (360 degrees) contains:

* 360 degrees x 60 minutes/degree = 21,600 minutes

* 21,600 minutes x 60 seconds/minute = 1,296,000 seconds

Example: A location at 75 degrees, 15 minutes, 30 seconds west longitude would be written as:

* 75° 15' 30" W

This system allows for incredibly precise location identification.