How can you tell what century something happened in?

To determine the century in which an event occurred, identify the year of the event and divide it by 100, rounding up if the year is not a multiple of 100. For example, events in the years 1901 to 2000 occurred in the 20th century, while events from 2001 to 2100 are in the 21st century. Generally, the first century spanned from the year 1 to 100, the second from 101 to 200, and so forth.