Strong Number or Not in C Program

Strong number or not in the C program.

In this article, you will learn how to check whether a given number is strong.

What is the strong number?

The sum of the factorial of the digits of the input number is equal to the number itself.

Example-1 A Strong Number

Example-2 Not a Strong Numer

You should know about the following topics in C programming to understand this program:

• If-else statement
• While loop in C
• Do-while loop in C
• For loop in C

1 - Strong Number or Not in C using While loop

// Strong Number or Not in C using While loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, factorial, reminder, sum = 0;

    // Step-1 Take input from the User
    printf("INPUT A NUMBER: ");
    scanf("%d", &num);

    // Step-2 Check input number should be positive
    if (num > 0)
    {
        int original = num, i;

        // Step-3 Use a loop to check the number
        while (num)
        {
            i = 1;
            factorial = 1;
            reminder = num % 10;
            while (i <= reminder)
            {
                factorial = factorial * i;
                i++;
            }
            sum = sum + factorial;
            num /= 10;
        }

        // Step-4  Compare the value of the sum of digits with the original input value
        if (sum == original)
            printf("%d IS A STRONG NUMBER.\n", original);
        else
            printf("%d IS NOT A STRONG NUMBER.\n", original);
    }
    else
        printf("Enter a positive number!\n");

    return 0;
}

Run

Output

2 - Strong Number or Not in C using Do-while loop

// Strong Number or Not in C using Do-while loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, factorial, reminder, sum = 0;

    // Step-1 Take input from the User
    printf("INPUT A NUMBER: ");
    scanf("%d", &num);

    // Step-2 Check input number should be positive
    if (num > 0)
    {
        int original = num, i;

        // Step-3 Use a loop to check the number
        do
        {
            i = 1;
            factorial = 1;
            reminder = num % 10;
            do
            {
                factorial = factorial * i;
                i++;
            } while (i <= reminder);

            sum = sum + factorial;
            num /= 10;
        } while (num);

        // Step-4  Compare the value of the sum of digits with the original input value
        if (sum == original)
            printf("%d IS A STRONG NUMBER.\n", original);
        else
            printf("%d IS NOT A STRONG NUMBER.\n", original);
    }
    else
        printf("Enter a positive number!\n");

    return 0;
}

Run

Output

3 - Strong Number or Not in C using For loop

// Strong Number or Not in C using For loop
#include <stdio.h>

// It's the main function of the program
int main()
{
    int num, factorial, reminder, sum = 0;

    // Step-1 Take input from the User
    printf("INPUT A NUMBER: ");
    scanf("%d", &num);

    // Step-2 Check input number should be positive
    if (num > 0)
    {
        // Step-3 Use a loop to check the number
        for (int k = num; k > 0; k /= 10)
        {
            factorial = 1;
            reminder = k % 10;

            for (int i = 1; i <= reminder; i++)
                factorial = factorial * i;
            sum = sum + factorial;
        }

        // Step-4  Compare the value of the sum of digits with the original input value
        if (sum == num)
            printf("%d IS A STRONG NUMBER.\n", num);
        else
            printf("%d IS NOT A STRONG NUMBER.\n", num);
    }
    else
        printf("Enter a positive number!\n");

    return 0;
}

Run

Output