Simple interest can be defined as the amount of interest we have to pay for a principal amount we have taken from a financial institution at a certain rate of interest. For a better understanding of this simple interest calculation C program, we always recommend you to learn the basic topics of C programming listed below:

This C program calculates the** Simple Interest (SI)**, given the **Principal Amount (p)**, **Rate of Interest (r)**, and **Time (n)**. Simple Interest (SI) is the amount of interest we need to pay for a certain principal amount that we took from a bank or some financial institution for a certain period of time at a rate of interest.

Simple Interest is calculated by using the formula "**SI = p*n*r /100**". Where

- '
**p**' is the Principal amount, - '
**n**' is the number of years. - '
**r**' is the rate of interest for the amount.

Let us take an example to understand better,

- suppose, the
**principal amount (p)**is 1000 - the
**number of years (n)**is**5** - the
**rate of interest (r)**is**10** - then, calculate the
**Simple Interest (SI)**using the formula as**(1000 * 5 * 10)/100. = 500**

that means, we have to pay **500** for **5** years.

Similarly, to calculate **Simple Interest** half-yearly and quarterly, we need the **principal amount**,** rate of interest**, and **time**.

Now let's see how we use this logic in the C program. After accepting user input for the **principal amount (p)**, **rate of interest (r)**, and **time (t)**. We define variables as `float`

datatype. In this C program, we use **5.2 f** precision, in which **5** represents the total number of digits and **2** is the number of decimal points. It is for getting a better viewing experience in the simple interest.

The library function `scanf`

is used to take the three values and stored them in variables. Then according to the Simple Interest Formula, these three values are multiplied together and divide that value by **100**, and store result in the variable '**si**';

**STEP 1:** Import the Header Libraries to use the built-in functions in the C program such as `stdio.h`

**STEP 2:** Use the **main()** function to start the execution of the C program.

**STEP 3:** Initialize some variables for the principal amount (p), simple interest (si), rate of interest (r), and number of years (n),

**STEP 4:** Accept the values from the user for the principal amount, rate of interest, and number of years using `printf`

and `scanf`

built-in functions in `stdio.h`

library. We use the `float`

datatype with some precision.

**STEP 5:** Calculate the simple interest using the formula **p*n*r/100**.

**STEP 6:** With help of the `printf`

function and `float`

datatype with some precision we print the values of **p. n, r,** and the Simple Interest (si) using C program syntax.

` ````
#include <stdio.h>
void main() {
float p, r, si;
int t;
printf("Enter the values of p, r and t\n");
scanf("%f %f %d", & p, & r, & t);
si = (p * r * t) / 100.0;
printf("Amount = Rs. %5.2f", p);
printf("Rate = Rs. %5.2f\n", r);
printf("Time = %d years\n", t);
printf("Simple interest = %5.2f\n", si);
}
```

Enter the values of p,r, and t 2000 8 3 Amount = Rs. 2000.00 Rate = Rs. 8.00% Time = 3 years Simple interest = 480.00