Pronic numbers are those numbers who can be written as a product of two consecutive integers.

It means, they are of the form: **P =** **n * (n + 1)**

For example, the number **56** can be written as **7 * 8**, that is, a product of two consecutive integers.

Hence, the number **56** is a Pronic number.

Pronic numbers are also called oblong numbers, heteromecic numbers, or rectangular numbers.

Some of the Pronic numbers are: 0, 2, 6, 12, 20, 30, 42, 56, 72, 90, 110 …

Below is a program that inputs a number, and checks whether it is a Pronic number or not.

import java.lang.Math; public class PronicNumber { static void checkForPronic(int number) { int squareRoot = (int)Math.sqrt(number); int product = squareRoot * (squareRoot + 1); if(product == number) System.out.println("The number is a Pronic number"); else System.out.println("The number is not a Pronic number"); } public static void main (String[] args) { Scanner input = new Scanner(System.in); System.out.print("Enter a Number: "); int number = input.nextInt(); checkForPronic(number); } }

The program runs on the following algorithm to check whether a number is Pronic or not.

- Calculate the square root of number and taking floor of the number by typecasting it to
- Find the product of the squareRoot and (squareRoot + 1), and then compare the product with the number.

We used the java.lang.Math function sqrt(), to calculate the square root.

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