JavaScript

In JavaScript, numbers are used for everything involving calculations — whether it’s counting, measuring, or even working with decimals. Unlike some other programming languages, JavaScript has only one type of number: it can be integer or floating-point (decimal).

---

✅ Basic Number Types

let integer = 100;         // Integer
let float = 99.99;         // Decimal number

Both are treated as number type:

console.log(typeof 100);     // Output: "number"
console.log(typeof 99.99);   // Output: "number"

---

📌 Number Operations

You can use basic math operators:

let a = 10;
let b = 3;

console.log(a + b);  // Addition (13)
console.log(a - b);  // Subtraction (7)
console.log(a * b);  // Multiplication (30)
console.log(a / b);  // Division (3.333...)
console.log(a % b);  // Modulus (1)

---

🔹 Decimal Precision

JavaScript sometimes gives unexpected results with floating-point math:

console.log(0.1 + 0.2); // Output: 0.30000000000000004 😬

💡 Tip: Use toFixed() to fix decimal places:

let sum = 0.1 + 0.2;
console.log(sum.toFixed(2)); // Output: "0.30"

---

🔹 Number Methods

Method	Description
toString()	Converts number to string
toFixed(n)	Rounds number to n decimal places
toPrecision(n)	Formats number to n digits total
parseInt()	Converts string to integer
parseFloat()	Converts string to float

Examples:

let num = 123.456;

console.log(num.toString());     // "123.456"
console.log(num.toFixed(1));     // "123.5"
console.log(num.toPrecision(4)); // "123.5"

---

🔹 Number Constants

console.log(Number.MAX_VALUE);      // Largest possible number
console.log(Number.MIN_VALUE);      // Smallest possible number
console.log(Number.POSITIVE_INFINITY); 
console.log(Number.NEGATIVE_INFINITY);
console.log(Number.NaN);            // Not a Number

---

🔹 Checking for Numbers

Function	Description
isNaN()	Checks if value is Not a Number
isFinite()	Checks if number is finite

console.log(isNaN("hello"));         // true
console.log(isFinite(100));          // true
console.log(isFinite(Infinity));     // false

---

🔹 Convert to Numbers

Number("123");       // 123
parseInt("123.45");  // 123
parseFloat("123.45") // 123.45

---

🔹 Math with Numbers

JavaScript also has a Math object for advanced calculations:

Math.round(4.7);      // 5
Math.floor(4.9);      // 4
Math.ceil(4.1);       // 5
Math.sqrt(25);        // 5
Math.pow(2, 3);       // 8
Math.random();        // Random number between 0 and 1

---

🧠 Summary

Feature	Example	Result
Integer	let x = 10;	10
Float	let y = 3.14;	3.14
Addition	x + y	13.14
Convert string	Number("42")	42
Format decimals	num.toFixed(2)	“xx.xx”

---