Final answer:
The base date for date and time data in Excel 2013 is December 31, 1899, which is the date that Excel uses as a starting point for all date and time calculations.
Step-by-step explanation:
The base date for date and time data in Excel 2013 is December 31, 1899. In Excel, dates are actually stored as numbers, with this base date represented as 1. Therefore, January 1, 1900, is stored as the number 2, and so on. This system allows for date calculations within Excel. When you enter a date into Excel, it is converted into a serial number that represents the number of days that have passed since the base date. Time values are stored as decimal fractions because they represent the fraction of a day.
For the context of Excel and computer systems, changing base dates or systems would be a significant challenge. The transition during the Year 2K, or Y2K, was already a large-scale problem for computer systems as they moved from the 1900s to the 2000s. This highlights the importance of maintaining consistent date and time calculations to avoid chaos in computing environments.