Learning Objective: Understand JavaScript’s flexible number handling and how to work with basic numbers.

What Are Numbers in JavaScript?

Numbers are a fundamental data type in JavaScript. Unlike some programming languages, you don’t need to specify whether a number is an integer or a float—JavaScript takes care of it for you. This is because JavaScript is dynamically typed.

Example: Dynamically Typed Numbers

In JavaScript:

const wholeNumber = 5; // Integer
const decimalNumber = 3.14; // Float

In other languages like C, you would need to explicitly declare the type:

int wholeNumber = 5;
float decimalNumber = 3.14;

In JavaScript, both integers and decimals fall under the same number type, simplifying how we work with them.

Basic Math Operations

You can perform all the standard math operations in JavaScript, such as addition, subtraction, multiplication, and division.

Examples:

const a = 10;
const b = 5;

console.log(a + b); // Addition: 15
console.log(a - b); // Subtraction: 5
console.log(a * b); // Multiplication: 50
console.log(a / b); // Division: 2

What About ?

, short for Not a Number, is a special numeric value in JavaScript. It often occurs when you try to perform an invalid mathematical operation.

Examples:

console.log("hello" * 3); // NaN

Interestingly, even though stands for "Not a Number," its type is still :

console.log(typeof NaN); // "number"

Why? In computing, is technically part of the numeric type system, even though it doesn’t represent a valid number.

Advanced Number Operations

We’re keeping it simple for now, but JavaScript also has operators for more advanced calculations, like modulus , exponentiation , and more.

You’ll learn about these in detail in the upcoming module, Operators and Equality, where we’ll explore:

• Arithmetic operators
• Logical operators
• Assignment operators
• Comparison and equality

For now, focus on getting comfortable with basic numbers and operations.

Interactive Activity

Let’s put this into practice:

1. Open VS Code and create a new file called .
2. Try the following:
   • Declare variables for:
     • A whole number (e.g., your lucky number).
     • A decimal number (e.g., a measurement or value like 3.14).
   • Perform addition, subtraction, multiplication, and division with these numbers.
   • Log the results to the console.

Example:

const whole = 7;
const decimal = 3.14;

console.log(whole + decimal); // Addition
console.log(whole - decimal); // Subtraction
console.log(whole * decimal); // Multiplication
console.log(whole / decimal); // Division

What’s Next?

You’ve just learned the basics of working with numbers in JavaScript. Keep practicing, as numbers are a key part of programming. In the next lesson, we’ll explore Booleans, which will help us add logic and decisions to our programs.

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