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README.md

JavaScript Math Object 🧮

📺 Video

Why the Math object in JavaScript is useful (5:37)

📝 Description

The Math object is a built-in JavaScript object that provides a collection of mathematical properties and methods. Learn how to perform common mathematical operations without writing complex algorithms yourself.

🎯 What You'll Learn

  • Math constants (PI, E)
  • Rounding methods (round, floor, ceil, trunc)
  • Power and square root functions
  • Absolute value and sign
  • Trigonometric functions (sin, cos, tan)
  • Min and max functions
  • When to use each method

🔧 HTML Structure

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>My Website</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <script src="index.js"></script>
</body>
</html>

🎨 CSS Styling

body{
    text-align: center;
    font-size: x-large;
}

💻 Code Examples

Complete Example from index.js

// Math = built-in object that provides a
//        collection of properties and methods

let x = 0;
let y = 2;
let z = 3;

// Try uncommenting different methods to see results:

// z = Math.round(x);
// z = Math.ceil(x);
// z = Math.floor(x);
// z = Math.trunc(x);
// z = Math.pow(x,y)
// z = Math.sqrt(x);
// z = Math.sin(x)
// z = Math.cos(x)
// z = Math.tan(x)
// z = Math.abs(x)
// z = Math.sign(x)
// z = Math.min(x,y,z)
z = Math.max(x,y,z)

console.log(z);

Math Constants

let PI = Math.PI
console.log(`PI: ${PI}`)  // PI: 3.141592653589793

Rounding Methods

let x = 3.21;
// let x = 3.99;

Math.round(x);  // 3 - Rounds to nearest integer
Math.floor(x);  // 3 - Always rounds down
Math.ceil(x);   // 4 - Always rounds up
Math.trunc(x);  // 3 - Removes decimal portion

Power and Root

let x = 81;
let y = 2;

Math.pow(x, y);    // 6561 - 81 to the power of 2
Math.sqrt(x);      // 9 - Square root of 81

Absolute Value and Sign

let x = -10;

Math.abs(x);   // 10 - Removes negative sign
Math.sign(x);  // -1 - Returns -1, 0, or 1 based on sign

Trigonometry

let x = 45;
// Input is in radians
Math.sin(x);      // Sine
Math.cos(x);      // Cosine  
Math.tan(x);      // Tangent

Min and Max

let x = 0;
let y = 2;
let z = 3;

Math.min(x, y, z);   // 0 - Returns smallest value
Math.max(x, y, z);   // 3 - Returns largest value

📊 Rounding Methods Comparison

Method 3.21 3.99 -3.21 -3.99
round() 3 4 -3 -4
floor() 3 3 -4 -4
ceil() 4 4 -3 -3
trunc() 3 3 -3 -3

📋 Practice Exercises

  1. Circle Calculator - Calculate area and circumference using Math.PI
  2. Distance Formula - Calculate distance between two points using Math.sqrt and Math.pow
  3. Random Dice - Combine with Math.random() to roll dice
  4. Grade Rounder - Round grades using different rounding methods

💡 Common Use Cases

// Calculate area of circle
const radius = 5;
const area = Math.PI * Math.pow(radius, 2);

// Distance between two points
const distance = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));

// Round to 2 decimal places
const price = 19.456;
const rounded = Math.round(price * 100) / 100;  // 19.46

🎯 Key Takeaways

  • Math is a built-in object (not a constructor)
  • No need to create an instance - use Math directly
  • All methods are static
  • Math.PI is a useful constant for circle calculations
  • Choose the right rounding method for your needs:
    • round() - nearest integer
    • floor() - always down
    • ceil() - always up
    • trunc() - remove decimals
  • Math.sign() returns -1, 0, or 1 based on number's sign
  • Trigonometric functions (sin, cos, tan) use radians, not degrees
  • Math.min() and Math.max() can accept multiple arguments

⏭️ Next Lesson

Random Number Generator

Duration: 5:37
Difficulty: Beginner
Category: Built-in Objects