**Which is greater: the number of seconds in a day or the number of hours in 10 years?**

There are 60 x 60 x 24 = 3600 x 24 = 86 400 seconds in a day.

There are 24 x 365 x 10 = 87 600 hours in 10 years, not counting the additional hours in leap years.

Therefore, the number of hours in 10 years is greater than the number of seconds in a day.