JavaScript Program to Check Triangular Number

Posted in JavaScript Tutorial

Updated on Oct 30, 2024

By Mari Selvan

👁️ 85 - Views

⏳ 4 mins

💬 1 Comment

JavaScript Program to Check Triangular Number

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, various mathematical properties of numbers often pique our interest. One such property is whether a number is a triangular number.

A triangular number or triangle number is the sum of the natural numbers up to a certain value.

In this tutorial, we'll delve into a JavaScript program to check if a given number is a triangular number.

📄 Example

Let's take a look at the JavaScript code that checks whether a given number is a triangular number.

isTriangularNumber.js

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// Function to check if a number is a triangular number
function isTriangularNumber(num) {
  // Formula to check triangular number
  const n = Math.sqrt(2 * num);
  return Math.floor(n) * (Math.floor(n) + 1) / 2 === num;
}

// Driver program
// Replace this value with your desired number
const number = 10;

// Check if the number is a triangular number
if (isTriangularNumber(number)) {
  console.log(`${number} is a triangular number.`);
} else {
  console.log(`${number} is not a triangular number.`);
}

💻 Testing the Program

To test the program with different numbers, simply replace the value of number in the code.

Output

10 is a triangular number.

Run the script to check if the given number is a triangular number.

🧠 How the Program Works

The program defines a function isTriangularNumber that checks if a given number is a triangular number using the formula.
Replace the value of number in the main program with the desired number to check.
The program then calls the isTriangularNumber function and logs whether the number is a triangular number or not.

📏 Between the Given Range

Let's take a look at the javascript code that checks and displays triangular numbers in the range of 1 to 50.

findTriangularNumbers.js

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// Function to check if a number is triangular
function isTriangular(num) {
    // Formula to check if a number is triangular
    return Math.sqrt(8 * num + 1) % 1 === 0;
}

// Function to find and display triangular numbers in the range 1 to 50
function findTriangularNumbers() {
    console.log("Triangular Numbers in the Range 1 to 50:");

    for (let i = 1; i <= 50; i++) {
        if (isTriangular(i)) {
            process.stdout.write(i + " ");
        }
    }

    console.log(); // Move to the next line for better readability
}

// Call the function to find and display triangular numbers
findTriangularNumbers();

💻 Testing the Program

Output

Triangular Numbers in the Range 1 to 50:
1 3 6 10 15 21 28 36 45

Run the script to see the triangular numbers in the range from 1 to 50.

🧠 How the Program Works

The program defines a function isTriangular that checks whether a given number is a triangular number using the triangular number formula.
It defines a function findTriangularNumbers that iterates through numbers from 1 to 50 and prints those that are triangular.
The main section calls the function to find and display triangular numbers in the specified range.

🧐 Understanding the Concept of Triangular Numbers

Before delving into the code, let's take a moment to understand the concept of triangular numbers.

A triangular number is the sum of the natural numbers up to a certain value, and it can be represented by the formula T_n = n * (n + 1) / 2, where n is a non-negative integer.

For example, T₃ = 1 + 2 + 3 = 6 is a triangular number.