Since the concept of "time" is a human construct and the idea of a definitive "beginning of time" is largely theoretical, it is not possible to determine the exact number of days that have passed since the beginning of time, assuming it even had a specific starting point.
However, if we consider the age of the universe, which is estimated to be approximately 13.8 billion years, we can make an estimate based on the average length of a year. A common convention is to use the average length of a year on Earth, which is roughly 365.25 days.
Using these figures, we can calculate an estimate:
13.8 billion years x 365.25 days/year = approximately 5.04 trillion days.
Please note that this is a rough estimation and can vary depending on the assumptions made. Additionally, this calculation only takes into account the age of the universe and does not account for time periods before its existence.