Time zones are each one of the [?] spherical sectors into which the Earth is divided. They divide the [?] º of the Earth’s sphere between [?] hours that complete a full turn around the Earth’s [?].

Each time zone measures [?] º (360º / 24 hours = 15º). 15º = [?] hour.

To calculate the time zone somewhere in the world, the [?] meridian is used as a reference point.
From that point, one [?] one hour for each time zone that is traveled through towards the East and one subtracts an hour each time zone that is traveled across towards the [?].