Pronic Number in Java: Definition, Explanation, Examples, and Practice Problems

A Pronic Number (also called a Rectangular Number or Oblong Number) is a number that is the product of two consecutive integers. These numbers appear in many mathematical problems and are a common topic in programming exercises involving number patterns.

What Is a Pronic Number?

A number N is a Pronic Number if it can be written as:

N = n × (n + 1)

That means the number is formed by multiplying two consecutive integers.

Examples of Pronic Numbers

• 0 = 0 × 1
• 2 = 1 × 2
• 6 = 2 × 3
• 12 = 3 × 4
• 20 = 4 × 5
• 30 = 5 × 6
• 42 = 6 × 7

How to Check if a Number Is Pronic?

Steps:

1. Loop from i = 0 up to the number.
2. Check if i × (i + 1) equals the number.
3. If yes → it is a Pronic Number.
4. If no match is found → not a Pronic Number.

Java Program to Check Pronic Number

import java.util.*;

public class PronicNumber {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int num = sc.nextInt();

        boolean isPronic = false;

        for (int i = 0; i * (i + 1) <= num; i++) {
            if (i * (i + 1) == num) {
                isPronic = true;
                break;
            }
        }

        if (isPronic) {
            System.out.println("Pronic Number");
        } else {
            System.out.println("Not a Pronic Number");
        }
    }
}

  

Examples Table

Number	Expression	Pronic?
6	2 × 3	Yes
20	4 × 5	Yes
56	7 × 8	Yes
15	Not applicable	No
30	5 × 6	Yes

3 Practice Challenges

Challenge 1: List Pronic Numbers

Write a Java program to print all Pronic Numbers between 1 and 10,000.

Challenge 2: Pronic Count in Array

Given an array of integers, count how many of them are Pronic Numbers.

Challenge 3: Next Pronic Number

Write a Java program to find the next Pronic Number after a given number.