Given number is z , determine whether this number is Armstrong Number or not. A positive integer number of n digits is called an Armstrong Number of order n if
abcd…=pow(a,n) + pow(b, n) +pow(c,n)+pow(d,n)+………, where a, b, c, d are digits of input number abcd….., n is the number of digits present in the number.
Approach
- First count the number of digits present in the given number z. Let the number of digits be n.
- For every digits present in the number z ,let digits are d1 , d2 , d3,…..;compute d1^n , d2^n , d3^n……..
- If the sum of all computed digits are equal to z i.e. d1^n+d2^n+d3^n+……..=z; it is an armstrong number, then print that this number is an armstrong number, else print this number is not an armstrong number.
Example:
153 is an armstrong number because
1^3+5^3+3^3=153
1634 is a 4 digit armstrong number because
1^4+6^4+3^4+4^4=1634
Java Program to check a number is Armstrong Number Or Not
public class ArmstrongNumber {
public static void main (String args[]) {
// code to enter a number you want to check armstrong number or not
Scanner sc = new Scanner(System.in);
System.out.println(“Enter the number you want to check whether armstrong number or not”);
int n = sc.nextInt();
int temp=n,digits=0,rev,sum=0;
//To find the number of digits:
while(temp>0) {
temp=temp/10;
digits++;
}
temp=n;
while (temp > 0) {
//To find the last digit
rem=temp%10;
//Sum up of the each digit to the power total number of digits present in the number
sum + = Math.pow(rem,digits);
//To remove the last digit
temp=temp/10;
}
if (sum==n) {
System.out.println(“The given number is an armstrong number”);
}
else
System.out.println(“The given number is not an armstrong number”);
}
}
}
If you don’t understand how to find the number of digits java program and how to sum up each digits of a number,
Check the following :
Java Program to count the number of digits in a given number
Let, Given number be n , count the number of digits present in this number
Example :
Input n= 9876
Output: 4
There are 4 digits in 9876 , which are 9 , 8 , 7 & 6.
Approach :
In this approach count the digits by removing the digits from the given number starting from right to left till the number is reduced to 0 . Here remove digits from right because rightmost digit can be removed by performing integer division by 10 . For eg : n=9876, then 9876/10 = 987.6=987(Integer Division ) .
import java.util.*;
public class CountDigits {
public static void main (String args[] ) {
Scanner sc = new Scanner ( System.in) ;
System.out.println(“Enter the number to count the digits in it”);
int num=sc.nextInt();
int temp=num,count=0;
// if the number is exactly 0 , it has 1 digit
if(temp==0) {
count=1 ;
} else {
//Loop runs until the number become 0
while (temp >0 ) {
temp=temp/10; //Removes the last digit
count++;
}
}
System.out.println(“Number of digits : ” + count);
}
}