Answer:
The day would be 3.125 seconds longer in 25 centuries.
Explanation:
Let's break it down.
Each year, 1250 microseconds are added to the planet's day.
We need to find how long a day would be in 25 centuries.
A century is 100 years.
A second is 1,000,000 microseconds.

The day would be 3.125 seconds longer in 25 centuries.