The Romans added January and February to the calendar but ran into a problem — math and superstition. Here's why February became the odd month out.

The ancient Egyptian calendar consisted of 365 days without ... the festival occurred at different times of the year. During the Roman occupation of Egypt from the mid-1st to mid-3rd centuries ...

By the third-century BCE, Egyptians followed a solar calendar that spanned 365 days with a leap year every four years, National Geographic reports. In ancient Rome, their calendar varied and ...

Roman King Numa Pompilius (715-673 BC) set about creating a calendar with equal-length months, the University of Chicago said. "When Numa Pompilius took reign [of Rome], he decided to make the ...