Why were the five days added in the Egyptian calendar?

The five extra days added to the Egyptian calendar, known as the "epagomenal days," were included to complete the 365-day solar year. These days fell outside the standard twelve months of 30 days each, totaling 360 days. The inclusion of these five days allowed the Egyptians to align their calendar with the annual solar cycle, ensuring that important agricultural and ceremonial events occurred at the correct times of the year. This adjustment reflected their advanced understanding of astronomy and the need for a practical calendar in their agricultural society.