🔢 Number Data Type

Last Updated: 7th October 2025

The Number is used to represent numeric values — both integers and decimals.

Hinglish Tip 🗣: Jaise maths me numbers hote hai (1, 2.5, -3), waise hi JS me bhi hum unhe variables me store kar sakte hain.

Declaring Numbers

You can declare numbers using let, const, or var.

let x = 10; // Integer
let y = 3.14; // Decimal (Float)
let z = -25; // Negative number

Special Number Values

ValueMeaningExample
InfiniTyPosiTive infiniTy1 / 0 → InfiniTy
-InfiniTyNegaTive infiniTy-1 / 0 → -InfiniTy
NaNNoT a Number"abc" / 5 → NaN
BigInTLarge inTeger values (-2^53-1 to 2^53-1)12345678901234567890n

Note: Agar koi value number me convert nahi ho sakti, toh result aata hai NaN.

Example

let a = 42;
console.log(typeof a); // "number"
console.log(typeof 3.14); // "number"
console.log(typeof NaN); // "number"
console.log(typeof Infinity); // "number"
let big = 123456789012345678901234567890n;
console.log(typeof big); // "bigint"

Note 🧠: In JS, NaN ka matlab “Not a Number” hota hai, par fir bhi iska type "number" hota hai 😅

Round a Number

JavaScript provides several methods to work with numbers easily — like rounding, converting strings to numbers, and checking validity.

Hinglish Tip 🗣: Ye methods help karte hain jab hume number ke sath calculation, rounding, ya type conversion karni hoti hai.

1. toFixed()

  • Rounds a number to a fixed number of decimal places.
  • Returns a string value.
let a = 9.8765;
console.log(a.toFixed(2)); // "9.88"

2. toPrecision()

  • Formats a number to a specified total number of digits.
  • Returns a string value.
let b = 123.456;
console.log(b.toPrecision(4)); // "123.5"

🎯 Exercises

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