On a compass, what do the outside numbers indicate?

The outside numbers on a compass indicate magnetic bearings, which are crucial for navigation. These values represent the angular measurement from magnetic north, which is the direction that the compass points based on the Earth's magnetic field. Understanding magnetic bearings is essential for accurate navigation since they allow mariners to determine their heading relative to the magnetic north.

When using magnetic bearings, navigators must also take into account the variation between true north and magnetic north, known as magnetic declination. This variation can differ based on geographic location and can change over time. A compass can become a reliable navigational tool, allowing mariners to determine their course as long as they are aware of how their magnetic bearings relate to true or geographic directions.

Other answers such as true bearings, compass heading, or geographical directions do not accurately describe what the outside numbers on a compass represent. True bearings are measured from true north, compass heading refers to the direction in which the vessel is facing irrespective of magnetic influence, and geographical directions refer more broadly to cardinal points rather than the specific magnetic reference indicated by the compass.