In this article, we are going to learn how to calculate Compound Interest using a C language program. The Compound Interest can be calculated by using a simple formula. The formula for Compound interest is:

#### Formula to calculate Compound Interest

```
Amount = Principal(1 + Rate/Num)^(NumTime)
```

#### Where:

**Amount**: This is the amount value including interest and principal.**Principal**: This is the amount borrowed on interest.**Rate**: This is the rate in % at which interest will be charged**Num**: This number tells us how interest will be compounded. For example, Quarterly, Half Yearly, Annually.**Time: This is the**time for which this money is borrowed.

The Compound interest earned can be calculated with the below calculation once you have the Amount.

```
CompoundInterest = Amount - Principal;
```

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### C Program to Calculate Compound Interest

Now let us see this formula in action using the C program below. We are asking the user to enter Principal, Interest, rate, and Time values and calculating the compound interest by using the above formula.

```
#include<stdio.h>
#include<math.h>
int main()
{
float PrincipalAmt, time, rate, num, Amount;
printf("Please enter the Principal Amount: ");
scanf("%f",&PrincipalAmt);
printf("Please enter the Rate of Interest: ");
scanf("%f",&rate);
printf("Please enter the Time: ");
scanf("%f",&time);
printf("Please enter the Number of Compounding: ");
scanf("%f",&num);
Amount = PrincipalAmt*pow( (1+(rate/num)), (num*time));
printf("The Amount will become : %.2f\n",Amount);
long CompoundInterest = Amount - PrincipalAmt;
printf("The Compound Interest Earned is : %.2f\n",CompoundInterest);
return 0;
}
```

Output

```
```