I’m copying the paragraphs from the book. (you can read it, because Egyptians myths are interesting to learn in my opinion, like Greek myths)
Goddess of the sky, Nut was married to the Earth God, Geb. Geb and Nut want to have kids, but the King of the Gods or Sun God, Ra heard the bad prophecy, that a child of Nut and Geb would replace Ra as the King of the Gods one day. So when Ra learned out that Nut was pregnant, he forbade Nut to give birth to her children on any day or night of the year (so Nut had to stay pregnant, forever) Then Nut figured out a way. She set a game of dice with the Moon God, Khons. Everytime Khons lost; he had to give nut some of his moonlight. He lost so many times, Nut won enough moonlight, to create FIVE NEW DAYS and tag them to the end of the year. The Egyptians calendar had three hundred sixty (360) articles in a circle, Nut created extra five days and added them to the end of the year, and days were not part of the regular years. A year has three hundred and sixty five (365) days and Nut suppose to have her children during those extra five days. So, Nut gave birth on those five days, one kid a day, in a row. When Ra found out, he was furious but it was too late. The children were already born, their names are;
Those five days are called as Demon Days [I have no idea the reason of why they named it as Demon Days] , those days were bad luck in ancient Egypt.
Source: The Kane Chronicles: THE RED PYRAMID (by Rick Riordan)
Rick Riordan was the author of Percy Jackson and the Olympian series (The Lightning Thief, The Sea of Monsters, The Titan’s Curse, The Battle of the Labyrinth and The Last Olympian, I admit it that all of those five books are brilliant. The words he used are not complicated or difficult or in dictionary, the words are in beginner or intermediate category not expert. I’m not expert or fluent in English, that’s why I understand the story in these books---- I read all of them)