In this post, we will learn how to write a simple interest program in Python by taking input from the user and also we will write this program using the function with a detailed explanation and algorithm.

But before we jump into the algorithm or programming part let’s first discuss the formula of simple interest.

## Formula of Simple Interest

Where,

• P = principal amount
• R = Rate of interest
• T = Time period

## Algorithm for Simple Interest

1. Take input from the user (`p`,`r`,`t`)
2. To store the result create a variable called `simple_interest` and do step-3
3. `simple_interest = (p * r * t)/100`
4. At last print the result (`print(simple_interest)`)

From the above algorithm, we understood how to write a Python program to calculate simple interest. So now let us do it practically.

Few programming concepts you have to know before writing this program:

### Source Code

``````p = int(input("Enter Principal Amount: "))
r = int(input("Enter Rate of Interest: "))
t = int(input("Enter Time Period: "))

simple_interest = (p*r*t)/100

print(f"Simple Interest is: {simple_interest}")``````

### Output

``````Enter Principal Amount: 50000
Enter Rate of Interest: 10
Enter Time Period: 3
Simple Interest is: 15000.0``````

Now let us modify the above program and write it using the function.

## Simple Interest Program in Python Using Function

Before writing this program Few programming concepts you have to know:

### Source Code

``````def Cal_SI(p,r,t):
return (p*r*t)/100

principal = int(input("Enter Principal Amount: "))
rate = int(input("Enter Rate of Interest: "))
time = int(input("Enter Time Period: "))

print(f"Simple Interest is: {Cal_SI(principal,rate,time)}")``````

### Output

``````Enter Principal Amount: 250000
Enter Rate of Interest: 7
Enter Time Period: 7
Simple Interest is: 122500.0`````` Hi, I'm Yagyavendra Tiwari, a computer engineer with a strong passion for programming. I'm excited to share my programming knowledge with everyone here and help educate others in this field.