Calculate Century

Calculator for the years of a century and its fractions. If only the number of a century is entered, then a span of one hundred years will be shown. Also, a numerator and a fraction (half, third, fourth, fifth) can be entered, like second half, to show the according span. At input errors, like fourth third, the output will be empty. At thirds, the years can't be divided equally, here the second third has 34 years, the other two have 33 years each. BCE means before common era.

Examples: the second quarter of the 19. century was from 1826 to 1850. The first half of the first pre-Christian century was 100 - 49 BCE.

There is no zeroth century, so the first digit of a century is one higher than the first digit of a year within, except for the first century BC and AD and except for the first year of a BC century and the last year of an AD century. This sounds more complicated than it is. The first century begins in the year 1 and ends in the year 100, the second century begins in the year 101 and ends in the year 200. The first century before our era begins in the year 100 BC and ends in the year 1 BC. The second century before our era begins in the year 200 BC and ends in the year 101 BC. The terms before and after our era and before and after Christ are used synonymously; they mean the same thing, but the first does not have the religious context.
There is also no year 0, which is why the year 1 before is immediately followed by the year 1 after. This must be taken into account when counting across the era change, so from the year 5 before to 5 after it is 5+5-1 = 9 years.