Sum Of A Geometric Progression Formula Calculator

Instructions: Use the following calculator as a series of examples. Perform the operation yourself and then check your answer by pressing the "=" key. If your answers do not match, check your work first. If you still do not understand refer to the definitions or incremental calculator page to review.
The following is the formula for calculating the sum of n terms of a geometric sequence of numbers.
Sn= a(1 - rn)/(1 - r)

Enter your own values into the boxes or press new example for computer generated numbers.
To use as a quiz, try to evaluate the expresion yourself and then check your answer. The calculator solves the following problem:
Find the sum of the first n terms of the geometric sequence which begins with a and changes with the multiplication of r.
a =   n =   r =
Sn

Definitions
Incremental Calculator
Intro Geometric Sum
Chapter 5