C Program To Calculate Amount In Compound Interest

When interest compounds q times per year at an annual rate of r % for n years, the principal p compounds to an amount a as per the following formula:

a = p (1 + r / q) ^nq

Write a C Program to read 10 sets of p, r, n & q and calculate the corresponding a‘s.

Related Read:
Basic Arithmetic Operations In C
For Loop In C Programming Language
C Program to Calculate the Compound Interest

Video Tutorial: C Program To Calculate Amount In Compound Interest

Logic To Find Compounded Amount

We ask the user to enter values for floating point variables p, n, r and q. We use the formula:

a = p (1 + r / q) ^nq

And display the result to the console window.

where,
p – principal amount;
n – number of years.
r – rate of interest;
q – number of times interest compounds per year.

Note: We need to convert the user entered interest into percentage by dividing the integer number by 100.

Source Code: C Program To Calculate Amount In Compound Interest

 
#include<stdio.h>
#include<math.h>

int main()
{
    float p, n, r, q, a;
    int count;

    for(count = 1; count <= 10; count++)
    {
        printf("Enter principal amount\n");
        scanf("%f", &p);

        printf("Enter number of years\n");
        scanf("%f", &n);

        printf("Enter rate of interest\n");
        scanf("%f", &r);

        r = r / 100;

        printf("Enter no of times you compound per year\n");
        scanf("%f", &q);

        a = p * pow( (1 + (r/q)), n * q );

        printf("Compounded amount is %f\n\n", a);
    }

    return 0;
}

Output
Enter principal amount
5000
Enter number of years
2
Enter rate of interest
8
Enter no of times you compound per year
4
Compounded amount is 5858.296875

Enter principal amount
1000
Enter number of years
7
Enter rate of interest
5
Enter no of times you compound per year
1
Compounded amount is 1407.100464

Enter principal amount
2000
Enter number of years
5
Enter rate of interest
12
Enter no of times you compound per year
12
Compounded amount is 3633.393311

Enter principal amount
5000
Enter number of years
5
Enter rate of interest
5
Enter no of times you compound per year
5
Compounded amount is 6412.160156

Enter principal amount

Note: Above program keeps on iterating 10 times and asks the input 10 times.

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