How many seconds are there in 2500 years? (assume 1 year=365 days) express your answer using three significant figures

The question gives us a conversion factor but we need more:

1 year= 365 days
1 day= 24 hours
1 hour= 60 min
1 min= 60 seconds

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later