A geometric series is a list of numbers where each number, or term, is found by multiplying the previous term by a common ratio r. If we call the first term a, then the geometric series can be expressed as follows:
We call this a finite geometric series because there is a limited number of terms (an infinite geometric series continues on forever.) In this example, there are 10 terms, the common ratio is r, and each of the terms of the geometric sequence follows the same pattern. The first term is a. The second term is the previous term a multiplied by r. The third term is the second term multiplied again by r to create , and so on until the last term.