*19*

### Introduction

Have you ever come across the term “Armstrong number” while learning C programming and wondered what it actually means? If so, you’re in the right place! This blog post is here to demystify the concept of Armstrong numbers and show you how to write a simple C program to check if a number is an Armstrong number. Whether you’re a beginner or just brushing up on your coding skills, this guide will walk you through everything you need to know in a straightforward and easy-to-understand way.

### What is an Armstrong Number?

An Armstrong number, also known as a narcissistic number, is a number that is equal to the sum of its own digits each raised to the power of the number of digits. In simpler terms, for a 3-digit number, each digit is cubed (raised to the power of 3) and then summed. If the resulting sum is equal to the original number, it’s an Armstrong number.

#### Example of Armstrong Number

Let’s take the number 153 as an example:13+53+33=1+125+27=1531^3 + 5^3 + 3^3 = 1 + 125 + 27 = 15313+53+33=1+125+27=153

Since 153 equals the sum of its digits raised to the power of 3, it is an Armstrong number.

### Writing a C Program to Check Armstrong Numbers

Now that we’ve covered the basics, let’s move on to writing a C program that can check whether a given number is an Armstrong number or not.

#### Step-by-Step Guide to Writing the Program

**Input the Number:**- The program will first prompt the user to enter a number.

**Calculate the Number of Digits:**- Determine how many digits the number has. This will dictate the power to which each digit will be raised.

**Compute the Sum:**- For each digit in the number, raise it to the power determined in the previous step and add the result to a sum.

**Compare the Sum to the Original Number:**- Finally, compare the computed sum to the original number. If they’re the same, the number is an Armstrong number.

### Explanation of the Code

**Including Libraries:**The program starts by including the standard input/output library (`stdio.h`

) and the math library (`math.h`

), which is necessary for using the`pow()`

function.**Variable Declaration:**We declare variables to store the user input (`num`

), the original number (`originalNum`

), the remainder of the division operation (`remainder`

), and the number of digits (`n`

).`result`

is a floating-point variable used to store the calculated sum.**Calculating the Number of Digits:**A loop divides the number by 10 repeatedly until it becomes zero. Each division reduces the number by one digit, and the loop counter (`n`

) tracks the number of divisions, which equals the number of digits.**Calculating the Sum:**Another loop is used to compute the sum of each digit raised to the power of`n`

. The`pow()`

function is used here.**Comparison and Output:**Finally, the computed sum is compared with the original number. If they match, the program prints that the number is an Armstrong number; otherwise, it states that it’s not.

### Conclusion

Understanding Armstrong numbers in C is an excellent way to practice your programming skills, especially in working with loops and mathematical functions. By following the step-by-step guide and experimenting with the code provided, you can easily master this concept and apply it to solve other related problems. So go ahead, give it a try, and see how many Armstrong numbers you can find!

### Frequently Asked Questions (FAQs)

**Q1: Can Armstrong numbers have more than three digits?**

Yes, Armstrong numbers can have more than three digits. For example, 9474 is an Armstrong number because 94+44+74+44=94749^4 + 4^4 + 7^4 + 4^4 = 947494+44+74+44=9474.

**Q2: What is the smallest Armstrong number?**

The smallest Armstrong number is 0 because 01=00^1 = 001=0.

**Q3: Is 407 an Armstrong number?**

Yes, 407 is an Armstrong number because 43+03+73=4074^3 + 0^3 + 7^3 = 40743+03+73=407.

**Q4: How do I modify the program to check Armstrong numbers with more than three digits?**

The provided C program already works for numbers with any number of digits. You don’t need to modify it.

**Q5: Why is the pow() function used in the C program?**

The

`pow()`

function is used to raise each digit to the power of the number of digits, which is essential for calculating whether a number is an Armstrong number.