# Write a C program to calculate Simple Interest

In this post, we will learn how to calculate simple interest using C programming language. Simple Interest is quick and easy method of calculating the interest amount for a particular principal amount of money at some rate of interest. So, Simple Interest is the simplest and the easiest way for determining how much extra you'll have to pay for your loan. For example, when a person takes a loan of Rs. 6000, at a rate of 10 p.a. for three years, the person's interest for three years will simple interest on the borrowed money.

## Simple Interest Formula

The Simple interest (S.I.) formula is given by -

```
SI = (P x T x R)/100
Where,
P is the principle amount
T is the time and
R is the rate
```

## C program to calculate Simple Interest

In the given program, we allow users to enter the principal amount, rate of interest, and number of years. By using these values, the following C program calculates simple interest -

```
#include <stdio.h>
int main()
{
float principle, time, rate, SI;
/* Input principle, rate and time */
printf("Enter the principal amount : ");
scanf("%f", &principle);
printf("Enter the number of years : ");
scanf("%f", &time);
printf("Enter the rate of interest : ");
scanf("%f", &rate);
/* Calculate simple interest */
SI = (principle * time * rate) / 100;
printf("Simple Interest = %f", SI);
return 0;
}
```

**Output 1**

```
Enter the principal amount : 10000
Enter the number of years : 4
Enter the rate of interest : 5
Simple Interest = 2000.000000
```

**Output 2**

```
Enter the principal amount : 9000
Enter the number of years : 9
Enter the rate of interest : 6
Simple Interest = 4860.000000
```

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