How To Check Whether a Number Is a Pronic Number or Not in Java?

Pronic number can be defined as a number when it is a product of two consecutive integers.

Mathematically, the Pronic number is in the form of n(n+1).

It is also called as heteromecic number, oblong number or rectangular number.

To show you some instances

Instance-1

Input number is 12

Let’s check it by using the logic of pronic number −

4 * 3 = 12, where 3 and 4 are two consecutive numbers.

Hence, 12 is a pronic number.

Instance-2

Input number is 30

Let’s check it by using the logic of pronic number −

5 * 6 = 30, where 5 and 6 are two consecutive numbers.

Hence, 30 is a pronic number.

Instance-3

Input number is 81

Let’s check it by using the logic of pronic number −

9 * 9 = 81, where 9 and 9 are not two consecutive numbers.

Hence, 81 is not a pronic number.

Some other examples of pronic numbers include 0, 2, 42, 56, 90, 110, 380, 420, 462 etc.

Note −

According to Wikipedia

• The only prime pronic number is 2.

• All pronic numbers are even.

Syntax

To get the square root of a specified number we can use the inbuilt sqrt() method which

is present in Math class of the java.lang package.

Following is the Syntax to get the square root of the number.

(We have typecasted to long)

long squareRoot = (long)Math.sqrt(inputNumber);

Algorithm

We can follow 2 algorithms here.

Algorithm 1

• Step 1 − Get an integer number either by initialization or by user input.

• Step 2 − Find the square root of the input number and round it to a lower integer. Suppose it is n.

• Step 3 − Find n+1.

• Step 4 − Then find n(n+1)

• Step 5 − If n(n+1) is equal to the original input number then it is a pronic number else it is not a pronic number.

Algorithm 2

• Step 1 − Get an integer number either by initialization or by user input.

• Step 2 − Take a for loop and iterate it from o to square root of the original number.

• Step 3 − And inside for loop keep on checking n*(n+1)

• Step 4 − If n(n+1) is equal to the original input number then it is a pronic number else it is not a pronic number.

Multiple Approaches

We have provided the solution in 2 different approaches.

• By Using Static Input Value and without Loop (Algorithm-1)

• By Using User Defined Method and with Loop (Algorithm-2)

Let’s see the program along with its output one by one.

Approach-1: By Using Static Input Value and without Loop

In this approach find square root say n then find n(n+1) and check if it's the same with the original number or not.

Here we have used Algorithm-1

Example

public class Main{
   //main method
   public static void main(String[] args){
   
      //initialized a number
      long inputNumber = 12;
      System.out.println("Given number: ");
      
      //Find square root of the input number
      //and assign it to a long variable say n
      long n = (long)Math.sqrt(inputNumber);
      
      //Check if the input number is eqaul to n(n+1)
      if(inputNumber==n*(n+1)){
         //print it is a pronic number
         System.out.println(inputNumber+" is a pronic number");
      } else {
         //else print it is not a pronic number
         System.out.println(inputNumber+" is not a pronic number");
      }
   }
}

Output

Given number:
12 is a pronic number

Approach-2: By Using User Defined and with Loop

In this approach the user will be asked to take the input of an integer value and then we will call a user defined method by passing this input number as parameter.

Inside the method we will check whether the number is a pronic number or not by using the algorithm.

Here we have used Algorithm-2

Example

import java.util.*;
public class Main{
   //main method
   public static void main(String[] args){
   
      //initialized a number
      int inputNumber = 110;
      System.out.println("Given number: "+inputNumber);
      
      //calling the user defined method
      boolean result = checkPronic(inputNumber);
      if(result)

      //print it is a pronic number
      System.out.println(inputNumber+" is a pronic number");

      else
      //else print it is not a pronic number
      System.out.println(inputNumber+" is not a pronic number");

   }
   public static boolean checkPronic(int inputNumber){
      //Find square root of the input number
      //and assign it to a long variable say n
      long n = (long)Math.sqrt(inputNumber);
         
      //iterate from i=0 to square root of number i.e n
      for(int i=0;i<=n;i++){
         
         //if i(i+1) equals with inputNumber
         if(inputNumber==i*(i+1))
         //return true
         return true;
      }
      //else return false
      return false;
   }
}

Output

Given number: 110
110 is a pronic number

In this article, we explored how to check a number whether it is a pronic number or not in Java by using different approaches.