Final answer:
The numbers for hours per day, days per week, and days per year are not exactly 24/7/365 because of the Earth's rotation and the calendar system we use.
Step-by-step explanation:
The reason the numbers for the hours per day, days per week, and days per year are not exactly 24/7/365 is primarily due to two factors.
The Earth's rotation is not precisely 24 hours. It takes the Earth 365.2422 solar days to complete its circuit, which is slightly longer than 365 days. As a result, a solar day is slightly longer than a sidereal day.
Another reason is related to the calendar system we use which has been adapted from ancient civilizations. The Julian calendar, introduced by Julius Caesar, approximated the year at 365.25 days. To account for the extra time, a leap year was added every four years, making the average length of the year 365.25 days.
These factors explain why the numbers are not exactly 24/7/365, but rather slightly longer due to the Earth's rotation and the calendar system we use.