In this section, we will explore the concept of spy numbers and develop Java programs to determine if a given number is a spy number or not. The spy number program is often encountered in Java coding assessments.
What is Spy Number?
A spy number refers to a positive integer where the sum of its digits is equal to the product of its digits. Put simply, a number is classified as a spy number if the sum and product of all its digits are the same.
Example of Spy Number
Let’s consider the number 1124 and determine if it is a spy number. We start by separating the number into its digits: 1, 1, 2, 4. Next, we calculate the sum and product of these digits.
Sum = 1 + 1 + 2 + 4 = 8
Product = 1 * 1 * 2 * 4 = 8
We observe that the sum and product of the digits are both equal to 8. Therefore, the number 1124 is a spy number.
Similarly, we can apply this process to other numbers as well. Some other examples of spy numbers include 22, 123, and 132.
Steps to Find Spy Number
- Read or initialize a number (n) that you want to check.
- Declare two variables, sum, and product, to store the sum and product of digits.
- Initialize sum with 0 and product with 1. Iteratively perform the following steps until the given number (n) becomes 0:
- Find the last digit of the given number by using the modulo operator: last digit = n % 10.
- Add the last digit to the variable sum: sum += last digit.
- Multiply the last digit with the product variable: product *= last digit.
- Divide the given number (n) by 10 to remove the last digit: n /= 10. If the sum and product of the variables have the same value, then the given number (n) is a spy number; otherwise, it is not a spy number.
Spy Number Java Program
SpyNumberExample.java
import java.util.Scanner;
public class SpyNumberExample
{
public static void main(String args[])
{
int num, product=1, sum=0, lastdigit;
// create object of scanner
Scanner sc = new Scanner(System.in);
System.out.print("Enter the number to check: " );
//reads an integer from the user and stores it in the variable num
num=sc.nextInt();
//executes untill the condition becomes false
while(num>0)
{
//finds the last digit of the number
lastdigit=num%10;
//adds last digit to the variable sum
sum=sum+lastdigit;
//calculates the product
product=product*lastdigit;
//removes the last digit from the given number
num=num/10;
}
//compares the sum and product
if(sum==product)
//prints if the above condition returns true
System.out.println("The given number is a spy number.");
else
//prints if the above condition returns false
System.out.println("The given number is not a spy number.");
}
}
Output 1:
Enter the number to check: 123 The given number is a spy number.
Output 2:
Enter the number to check: 456 The given number is a not spy number.
SpyNumberExample1.java
import java.util.Scanner;
public class SpyNumberExample1
{
//method to check the Spy number
private static boolean isSpyNumber(int number)
{
int lastDigit = 0;
int sum = 0;
int product = 1;
//executes until the condition returns true
while(number != 0)
{
//determines the last digit of the given number
lastDigit = number % 10;
//adds the last digit to the variable sum
sum = sum + lastDigit;
//multiply last digit with product
product = product * lastDigit;
//removes the last digit of the given number
number = number / 10;
}
//compares the variable sum with product and returns the result accordingly
if(sum == product)
return true;
return false;
}
//driver code
public static void main(String args[])
{
int lowerRange = 0, upperRange = 0;
Scanner sc = new Scanner(System.in);
System.out.print("Enter the lower range: ");
//reads lower range
lowerRange = sc.nextInt();
System.out.print("Enter upper range: ");
//reads the upper range
upperRange = sc.nextInt();
System.out.println("The Spy numbers between "+ lowerRange + " to "+ upperRange+" are: ");
for(int i=lowerRange; i<=upperRange; i++)
{
//calling user-defined function that checks if the given number is spy or not
if(isSpyNumber(i))
//prints all the spy numbers
System.out.print(i +" ");
}
}
}
Output:
Enter the lower range: 1 Enter upper range: 10000 The Spy numbers between 1 to 10000 are: 1 2 3 4 5 6 7 8 9 22 123 132 213 231 312 321 1124 1142 1214 1241 1412 1421 2114 2141 2411 4112 4121 4211
We hope you now have a better understanding of Spy Number in Java. To expand your knowledge further, be sure to follow tutorials.freshersnow.com.