Armstrong Number in Java - What is an Armstrong number
Armstrong Number in Java
A number is said to be an Armstrong number when the summation of each
digit cube of a number is equal to the original number.
Example 0, 1, 153, 370, 371, 407 etc.
Let’s check 153 is an Armstrong number or not.
153 = (1 * 1 * 1) + (5 * 5 * 5) + (3 * 3 * 3)
153 = 1 + 125 + 27 is equal to 153.
Check another number 407 is an Armstrong number or not.
407 = (4 * 4 * 4) + (0 * 0 * 0) + (7 * 7 * 7)
407 = 64 + 0 + 343 is equal
to 407 so it is an Armstrong
Java program to check Armstrong's number.
public class ArmstronNumber
{
public static void
main(String args[])
{
int num; // Number to Check Armstrong no.
int temp; // temp variable to store the number
int digit; // last digit taker
int arm=0; // variable to store the cube of a digit
num = 153; // number to be checked
temp = num; // store the number
while(num != 0)
{
digit = num %
10;
arm = arm + digit * digit * digit;
num = num / 10;
}
if(temp == arm)
System.out.println("Armstrong
Number");
else
System.out.println("Not Armstrong number");
}
}
In the above program, we have taken 153 as an example for checking
the Armstrong number. We have taken each digit cube and summed it up to
variable arm then check it, if it is equal to 153 then it is an Armstrong number.
Java Program to Check Armstrong Number with method
import java.util.*;
public class ArmstronNumWithMethod
{
int num; // Number to Check Armstrong no.
int digit; // last digit taker
int arm=0; // variable to store the cube of a
digit
// method
int armstronNumber(int
n)
{
num = n;
while(num != 0)
{
digit = num %
10;
arm = arm + digit * digit * digit;
num = num / 10;
}
return arm;
}
// main method started
public static void
main(String args[])
{
int number, armNum;
Scanner sc = new
Scanner(System.in);
// object of the
class
ArmstronNumWithMethod ob = new ArmstronNumWithMethod();
System.out.println("Enter a number :");
number =
sc.nextInt();
// call the method
with number as parameter
armNum =
ob.armstronNumber(number);
if(number == armNum)
System.out.println(number + " is Armstrong Number");
else
System.out.println(number + " is not Armstrong number");
} // main method end
} // end of class
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Nearest prime pair number in java - Program to print nearest prime for a given number
Nearest prime pair number in java - Program to print the nearest prime for a given number
In the following program, it generates a nearest prime number of a given
number. This program takes a number in the main() method and then it passed to a
for loop and from there it checks the prime number with its closest. Suppose when
we enter 15 it will print the nearest prime pair number as follows:
11, 13, and 17, 19.
import java.util.*;
class NearestPrimeNumber
{
public boolean isPrime(int number)
{
int i,flag = 1;
for(i=2;i<number;i++)
{
if(number % i==0)
{
flag = 0;
break;
}
}
if(flag == 1)
{
return(true);
}
else
return(false);
}
public static void main(String args[])
{
Scanner in=new Scanner(System.in);
NearestPrimeNumber ob=new NearestPrimeNumber();
int i,m,num,temp = 0;
System.out.println("Enter a number");
num=in.nextInt();
for(i=num-1;i>=1;i--)
{
if(ob.isPrime(i))
{
temp = i + 2;
if(ob.isPrime(temp))
{
System.out.println("nearest prime pair is");
System.out.println(i + " , "+ temp);
break;
}
}
}
for(i=num ; ; i++)
{
if(ob.isPrime(i))
{
m=i-2;
if(ob.isPrime(m))
{
if(temp != i)
{
System.out.println(m+" , "+i);
break;
}
else
{
break;
}
}
}
}
}
}
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Perfect number in java - Write a program to find perfect number or not
Perfect number in java
A perfect number is a positive number (integer number) is the sum total of its factor
except for the number itself. For example 6, has factor 1, 2, 3 (except 6) and add
it all 1 + 2 + 3 = 6. Here summation of its divisors (excluding the number) is
equal to the original number.
In the
following code a number is taken by the user in n = sc.nextInt() and then with With the help of for loop, we do a summation of its divisor, less them the number. After
then with the help of if condition statement
if(s == n)
System.out.println("Perfect
Number");
else
System.out.println("Not a perfect
Number");
We check
the number is equal to the calculated summation in s. if both are equal then
the number is the perfect number.
import
java.util.*;
public
class PerfectNumber
{
public static void main(String args[])
{
int i, s=0, n;
Scanner sc=new Scanner(System.in);
System.out.println("Enter a number
:");
n=sc.nextInt();
for(i=1; i<n; i++)
{
if(n % i == 0)
s = s + i;
}
if(s == n)
System.out.println("Perfect
Number");
else
System.out.println("Not a perfect
Number");
}
}
Perfect number in java with the method.
The below
program is done with the help of a method
int
perfectNumber(int num)
{
sum = 0;
number = num;
for(i=1; i<number; i++)
{
if(number % i == 0)
sum =sum + i;
}
return sum;
}
In the
above piece of code we do the same calculation as above but within a block
called perfectNumber(int num) where the supplied number is sum up of its factor
(except the number itself) and return to
the value. Then in the main() method, it checked the original number and if it
is equal to the return value then that number is a perfect number.
import java.util.*;
public
class PerfectNumberMethod
{
private int i; // for iteraion
private int sum; // for summation of factor
private int number; // number to check
perfect number
int perfectNumber(int num)
{
sum = 0;
number = num;
for(i=1; i<number; i++)
{
if(number % i == 0)
sum =sum + i;
}
return sum;
} // end of perfect method
// main method started
public static void main(String args[])
{
int i, s, n;
PerfectNumberMethod ob = new
PerfectNumberMethod();
Scanner sc=new Scanner(System.in);
System.out.println ("Enter a
number :");
N = sc.nextInt();
s = ob.perfectNumber (n);
if(s == n)
System.out.println ("Perfect
Number");
else
System.out.println ("Not a
perfect Number");
}
}
Perfect number in java using recursion
import
java.util.*;
public
class PerfectNumberWithRecursion
{
int sum, number, i;
PerfectNumberWithRecursion()
{
sum = 0;
i = 1;
}
int perfectNumber(int num)
{
number = num;
if(i<=number/2)
{
if(number%i==0)
{
sum =sum + i;
}
i++;
perfectNumber(number);
}
return sum;
}
// main method started
public static void main(String arg[])
{
int n, s;
Scanner sc=new Scanner(System.in);
System.out.println("Enter a
number");
n=sc.nextInt();
PerfectNumberWithRecursion ob=new
PerfectNumberWithRecursion( );
s = ob.perfectNumber(n);
if(s == n)
System.out.println(n + " is a
perfect number");
else
System.out.println(n + " is
not a perfect number");
}
}
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