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What is the Math Object?

The Math object is a built-in JavaScript object that provides mathematical functions and constants. Think of it as a super-powered calculator!

Basic Example

⚡ javascript

// Math is always available, no setup needed!
console.log(Math.PI)              // 3.141592653589793
console.log(Math.round(4.7))      // 5
console.log(Math.max(10, 20, 5))  // 20

Key Points:

Math is a built-in object (always available)
All Math methods are used with Math. prefix
Most methods work with numbers
Great for games, calculations, and algorithms

Rounding Numbers

There are different ways to round numbers depending on what you need!

Math.round() - Normal Rounding

⚡ javascript

// Rounds to nearest integer
console.log(Math.round(4.3))   // 4
console.log(Math.round(4.5))   // 5
console.log(Math.round(4.7))   // 5
console.log(Math.round(-4.5))  // -4

Math.floor() - Always Round Down

⚡ javascript

// Rounds down to nearest integer
console.log(Math.floor(4.3))   // 4
console.log(Math.floor(4.9))   // 4
console.log(Math.floor(-4.3))  // -5 (down on number line)

Math.ceil() - Always Round Up

⚡ javascript

// Rounds up to nearest integer
console.log(Math.ceil(4.1))    // 5
console.log(Math.ceil(4.9))    // 5
console.log(Math.ceil(-4.9))   // -4 (up on number line)

round()

Nearest integer

4.5 → 5

floor()

Round down

4.9 → 4

ceil()

Round up

4.1 → 5

Useful Math Methods

Finding Max and Min

⚡ javascript

// Find the largest number
console.log(Math.max(5, 10, 3, 8))     // 10
console.log(Math.max(-5, -10, -3))     // -3
 // Find the smallest number
console.log(Math.min(5, 10, 3, 8))     // 3
console.log(Math.min(-5, -10, -3))     // -10
 // Works with many numbers
console.log(Math.max(1, 2, 3, 4, 5, 100))  // 100

Absolute Value

⚡ javascript

// Make any number positive
console.log(Math.abs(5))      // 5
console.log(Math.abs(-5))     // 5
console.log(Math.abs(-42.7))  // 42.7
 // Useful for distance calculations
const distance = Math.abs(10 - 25)  // 15

Power and Square Root

⚡ javascript

// Raise to a power
console.log(Math.pow(2, 3))    // 8 (2 * 2 * 2)
console.log(Math.pow(5, 2))    // 25 (5 * 5)
console.log(Math.pow(10, 0))   // 1
 // Square root
console.log(Math.sqrt(16))     // 4
console.log(Math.sqrt(25))     // 5
console.log(Math.sqrt(2))      // 1.414...

Math Constants and Random

Important Constants

⚡ javascript

// PI - ratio of circle circumference to diameter
console.log(Math.PI)  // 3.141592653589793
 // Calculate circle area
const radius = 5
const area = Math.PI * Math.pow(radius, 2)
console.log(area)  // 78.54
 // E - Euler's number (for advanced math)
console.log(Math.E)  // 2.718281828459045

Math.random() Preview

⚡ javascript

// Generates random number between 0 and 1
console.log(Math.random())  // 0.7234...
console.log(Math.random())  // 0.3891...
console.log(Math.random())  // 0.9123...
 // We'll learn more about this in the next lesson!

Real-World Examples

⚡ javascript

// Calculate discount
const price = 29.99
const discount = 0.20
const finalPrice = Math.round(price * (1 - discount) * 100) / 100
console.log(\`$\${finalPrice}\`)  // $24.00
 // Distance between two points
const x1 = 0, y1 = 0
const x2 = 3, y2 = 4
const distance = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2))
console.log(distance)  // 5

Challenge: Math Explorer

Enter two numbers and see all the Math operations in action!

First Number:

Second Number: