This week I learned about finite geometric series and how to find the general term ($t_n$) along with how to find the sum of whatever the term number is.

To find $t_n$, you need $t_1$ and the common ratio

In this example I’m looking for $t_{13}$ with a $t_1$ of 5 and a common ratio of 2

And in this next example I show how to find $S_{13}$ with the same numbers.