PM 2Ring wrote:You're very close. Have you studied Mathematical Induction yet?

BTW, you need to use braces to group stuff for LaTeX, like this:

[math]S_n = S_{n-1} + S_{n-1}*i[/math]

Yes I have and thank you. I wondered whether i might have to do it by induction. I will let you know how it goes.

Thank you once again.