# Python Program to find the Sum of Geometric Progression

In this tutorial, we will discuss a Python program to find the sum of a geometric progression (GP) .

Before going to the program first, let us understand what is a *Geometric Progression(GP).*

**Geometric Progression(GP):**

- A geometric progression is a sequence of numbers where each term after the first is found by multiplying the previous term by a constant called the common ratio.
- The sum of the first $n$ terms of a GP is given by the formula: $S_{n}=a(−r−r )$ for $r1$, where $a$ is the first term and $r$ is the common ratio.

**Related: **Python Program for Simple Calculator

#### Program code for Geometric Progression in Python

# Sum of a Geometric Progression in Python def sum_of_gp(a, r, n): if r == 1: return a * n else: return a * (1 - r ** n) / (1 - r) a = float(input("Enter the first term (a): ")) r = float(input("Enter the common ratio (r): ")) n = int(input("Enter the number of terms (n): ")) sum_gp = sum_of_gp(a, r, n) print(f"The sum of the first {n} terms of the GP is {sum_gp}.")

#### Explanation

**Function Definition**: The`sum_of_gp`

function takes three parameters:`a`

,`r`

, and`n`

, and returns the sum of the first $n$ terms of the GP.**Main Program**: The program prompts the user to enter the first term, common ratio, and number of terms. It then calculates the sum of the GP using the`sum_of_gp`

function and prints the result.

#### Output

- When you run the above program, it will prompt you to enter the first term, common ratio, and number of terms.
- After entering the values, it will calculate the sum of the GP and print the result.

#### Conclusion

- In this tutorial, we learned how to find the sum of a geometric progression (GP) using a Python program.
- Understanding this concept is essential for solving various mathematical problems and enhancing your programming skills.