A triennial event happens every three years.
Something that happens every six years is sexennial.
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Something that happens every three years is a triennialevent.
7 of 10 leap years occur every years?
Something that happens once a century.
This happens on average of once every 7 years- 4 times in every 28-year cycle of the calendar. It happens whenever March first is a Friday..
As far as I know, nothing special happens every 100,000 years. A full precession cycle takes about 26,000 years.
You get 7 years of bad luck.
Quinquennial = something that happens every 5 years. Lustral = also something that happens every 5 years or we could invent: semi-Decennial: where semi is half and Deccennial happens every 10 years.
It happens every 200 years.
The Olympics.