In this tutorial, we will learn how to calculate Simple Interest using Python. Simple interest is a method of calculating the interest charge on a loan or deposit, based on the original principal amount, interest rate, and the time period for which the money is borrowed or invested. The formula for calculating simple interest is:

    Simple Interest (SI) = (Principal Amount * Rate of Interest * Time) / 100

Where:

• Principal Amount (P) is the initial amount of money.
• Rate of Interest (R) is the annual interest rate (as a percentage).
• Time (T) is the time period for which the money is borrowed or invested, typically in years.

Now, let’s look at the Python code to calculate Simple Interest:

Python Code

# Simple Interest Calculator in Python

# Function to calculate simple interest
def calculate_simple_interest(principal, rate, time):
    # Calculate simple interest
    simple_interest = (principal * rate * time) / 100
    return simple_interest

# Main program to take user input and display the result
def main():
    # Taking user inputs
    principal = float(input("Enter the principal amount: "))
    rate = float(input("Enter the rate of interest (in percentage): "))
    time = float(input("Enter the time period in years: "))
    
    # Calculate simple interest
    interest = calculate_simple_interest(principal, rate, time)
    
    # Display the result
    print(f"The Simple Interest is: {interest}")
    print(f"The total amount (Principal + Interest) is: {principal + interest}")

# Run the program
if __name__ == "__main__":
    main()

Explanation of the Program

The Python program has the following components:

• Function: calculate_simple_interest(principal, rate, time): This function takes three inputs: the principal amount, the rate of interest, and the time period. It calculates and returns the simple interest using the formula provided above.
• Main Program: The main program prompts the user to input the principal amount, the rate of interest, and the time period. It then calls the calculate_simple_interest function to compute the interest, and displays both the interest and the total amount (Principal + Interest).
• Input and Output: The program uses the input() function to take user input for the principal, rate, and time. The print() function is used to display the results to the user.
• Program Execution: The program is executed using the main() function, which is called only if the script is run directly (not imported as a module). The if __name__ == "__main__" block ensures this.

How to Run the Program

Follow these steps to run the program on your local machine:

1. Ensure that Python is installed on your system. You can download and install Python from the official website: https://www.python.org/downloads/.
2. Copy the Python code provided above into a text editor (like Notepad on Windows, or TextEdit on macOS) and save the file with a .py extension, for example, simple_interest.py.
3. Open the terminal (command prompt on Windows, Terminal on macOS or Linux).
4. Navigate to the directory where you saved the simple_interest.py file using the cd command.
5. Run the program by typing the following command and pressing Enter:

   python simple_interest.py

6. Enter the required inputs when prompted (principal, rate, and time). The program will output the calculated simple interest and the total amount.

Example

Suppose you have the following inputs:

• Principal: 1000
• Rate of Interest: 5%
• Time: 2 years

The program will output the following result:

    The Simple Interest is: 100.0
    The total amount (Principal + Interest) is: 1100.0

That’s it! You’ve successfully created a simple interest calculator using Python.