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. For example, 153 is an armstrong number in java:
1
3
+
5
3
+
3
3
=
1
+
125
+
27
=
153
1
3
+5
3
+3
3
=1+125+27=153
Find the number of digits in the number.
Extract each digit and compute its power raised to the total number of digits.
Sum these powered values.
If the sum equals the original number, it is an Armstrong number.
Java Implementation
Below is a simple Java program to check if a given number is an Armstrong number:
java
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import java.util.Scanner;
public class ArmstrongNumber {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (isArmstrong(number)) {
System.out.println(number + " is an Armstrong number.");
} else {
System.out.println(number + " is not an Armstrong number.");
}
scanner.close();
}
public static boolean isArmstrong(int num) {
int originalNum = num, sum = 0;
int numDigits = String.valueOf(num).length();
while (num > 0) {
int digit = num % 10;
sum += Math.pow(digit, numDigits);
num /= 10;
}
return sum == originalNum;
}
}
Explanation of the Code
We take user input using Scanner.
The isArmstrong() method computes whether the number is Armstrong by:
Finding the number of digits.
Extracting each digit and raising it to the power of the digit count.
Summing the results and comparing them with the original number.
If the computed sum matches the original number, it is an Armstrong number.
Example Outputs
Input:
yaml
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Enter a number: 9474
Output:
csharp
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9474 is an Armstrong number.
Input:
css
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Enter a number: 123
Output:
csharp
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123 is not an Armstrong number.
Checking Armstrong Numbers in a Range
If you want to find all Armstrong numbers in a given range (e.g., 1 to 10000), modify the program to iterate over the range:
java
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public class ArmstrongRange {
public static void main(String[] args) {
int start = 1, end = 10000;
System.out.println("Armstrong numbers between " + start + " and " + end + ":");
for (int i = start; i <= end; i++) {
if (isArmstrong(i)) {
System.out.print(i + " ");
}
}
}
public static boolean isArmstrong(int num) {
int originalNum = num, sum = 0;
int numDigits = String.valueOf(num).length();
while (num > 0) {
int digit = num % 10;
sum += Math.pow(digit, numDigits);
num /= 10;
}
return sum == originalNum;
}
}
Conclusion
Armstrong numbers are an interesting mathematical concept that can be easily implemented in Java using loops and mathematical operations. This concept is often used in coding challenges and programming exercises to strengthen understanding of loops, conditionals, and number manipulation.
