Find the number of terms in the geometric series 5+.15+...+3645

Answer 1

This makes no sense.
Looking at your first two terms, the common ratio is .15/5 = .03
so the terms would be getting smaller quite rapidly.
No way a term can be 3645
Is there a missing decimal somewhere??

Answer 2

I suspect that .15 is supposed to be 15, since 15/5 = 3 and 3645/5 = 729 = 3^6
so there are 7 terms