Variation becomes greater as you travel further away from the zero curve. Variation is also measured in degrees. For very accurate compass readings, it is necessary to adjust your compass to eliminate this error. Compasses can be adjusted to compensate for differences between magnetic and true North. This means you change the declination setting on your compass by 21 degrees towards the East.
Maps usually list the variation right on the map.
If the magnetic needle points East of true North, it is called East declination. If it points West, it is called West declination. The compass now automatically reads true North. A bearing is the degree reading or direction from your position to another object. For example, if you are in the field and a mountain peak is directly East of your position, the bearing of the mountain would be 90 degrees.