make the numbers smaller. Computations in these systems are just a matter of addition and subtraction.

Other calendars have one (or multiple) larger units of time.

Calendars that contain one level of cycles:
* week and weekday - this system (without year, the week number keeps on increasing) is not very common
* year and ordinal date within the year, e.g., the ISO 8601 ordinal date system

Calendars with two levels of cycles:
* year, month, and day - most systems,

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