In this tutorial, we are going to learn the writing program in c to calculate the Simple Interest. Simple Interest is a mathematical term and we have a mathematical formula for this calculation.

Before starting writing the program let’s understand simple interests.

## What is Simple Interest?

Simple interest is a method to calculate the interest charged on a loan. It is calculated by multiplying the interest rate by the principal by the number of days that elapse between payments.

**Simple Interest Formula:**

**SI = (P*T*R)/100**

**Where,**

**P is princip**le** amount**

**T is the time duration**

**R is the rate of interest**

**Example of how we can calculate simple interest**

**Input**

Enter principle: 1200

Enter time: 2

Enter rate: 5.4

**Output**

Simple Interest = 129.600006

## Logic we are following to calculate simple interest

- We are taking Principle amount, time and rate of interest as an input.
- Now after taking input we are simply calculating simple interest using formula
`SI = (principle * time * rate) / 100`

. - After calculating SI using above formula we are printing the value which is our program output.

## Program in C to calculate Simple Interest

```
#include <stdio.h>
int main()
{
float p, t, r, SI;
printf("Program to calculate Simple Interest\n");
printf("Enter principle amount: ");
scanf("%f", &p);
printf("Enter time (in years): ");
scanf("%f", &t);
printf("Enter rate: ");
scanf("%f", &r);
SI = (p * t * r) / 100;
printf("Simple Interest = %.2f", SI);
return 0;
}
```

**Output**

```
Program to calculate Simple Interest
Enter principle amount: 1000
Enter time (in years): 3
Enter rate: 5
Simple Interest = 150.00
```

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