## Python program to print Geometric progression or GP:

In this post, we will learn how to print the *Geometric progression* or *GP* in Python. We will take the *first number*, *common ratio* for the GP and total number of elements(*n*) to print in the series.

### How Geometric progression works:

Let’s try to understand how *Geometric progression* works. *Geometric progression* or *Geometric session* or *GP* is a *series of numbers* where each number is calculated by multiplying the *previous number* by a *constant value*. This *constant value* is called *common ratio*.

For example, *5, 10, 20, 40…* is a *Geometric progression* with *common ratio* *2*.

If *a* is the starting number and *r* is *common ratio*, then a *Geometric progression* looks like *a, ar, ar^2, ar^3…*.

So, for the *nth* number in a *Geometric progression* is *a * r^(n - 1)*. To print a *Geometric progression*, we can take the *first number*, value of *common ratio* and *total* numbers to print as inputs from the user.

Let me show you the algorithm that we will use to write the program.

## Algorithm for Geometric progression:

Below algorithm we will use to print a *GP*:

- Take the value of the
*start number*,*common ratio*and*total numbers*to print as inputs from the user. -
Run a loop to print the series for

*total numbers*of time.- Assign
*start number*to a variable. This variable will hold the*last value*of the series. - Print the
*last value*variable. - Update the
*last value*variable by multiplying it with*common ratio*. - Move to the next iteration.

- Assign
- Once the loop ends, exit from the program.

## Python program:

Below is the complete python program to print *Geometric progression*:

```
def print_geometric_progression(a, r, n):
current_value = a
for i in range(n):
print(current_value, end=' ')
current_value = current_value * r
a = int(input('Enter the first element: '))
r = int(input('Enter the common ratio: '))
n = int(input('Enter total numbers to print: '))
print_geometric_progression(a, r, n)
```

Here,

- We are taking the
*first element*as user input and storing that in the variable*a*. Similarly,*common ratio*is stored in*r*and*total numbers*is stored in*n*. -
*print*method is used to print the*geometric*progression*geometric progression*. It takes*a*,*r*, and*n*as its parameters.- It keeps the value of
*a*in*current_value*variable, which is the value to print. - The
*for loop*runs for*n*number of times. - On each iteration, it prints
*current_value*and changes it to*current_value * r*.

- It keeps the value of

### Output:

If you run this program, it will print output as like below:

```
Enter the first element: 4
Enter the common ratio: 3
Enter total numbers to print: 5
4 12 36 108 324
```

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