Day 6: Numbers & Math Made Easy

🔣 Working with Numbers

const score = 400;
console.log(score); // 400

const balance = new Number(100);
console.log(balance);            // [Number: 100]
console.log(balance.toString()); // "100"
console.log(balance.toString().length); // 3
console.log(balance.toFixed(1)); // "100.0"

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🧮 Example:

const otherNumber = 123.8966;
console.log(otherNumber.toPrecision(4)); // "123.9"

const hundreds = 1000000;
console.log(hundreds.toLocaleString('en-IN')); // "10,00,000"

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🔢 JavaScript Math Object

console.log(Math); // Full Math object

🔧 Common Math Methods

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🎲 Generating Random Numbers

console.log(Math.random());              // 0 to 0.999...
console.log((Math.random() * 10) + 1);   // 1 to 10.999...
console.log(Math.floor(Math.random() * 10) + 1); // 1 to 10

🧠 Random Number Between a Range (min to max)

const min = 10;
const max = 20;

console.log(Math.floor(Math.random() * (max - min + 1)) + min);

✅ This gives you a number between 10 and 20 (inclusive).

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❓ Interview Q&A

1. What’s the difference between toFixed() and toPrecision()?
   → toFixed() fixes decimal places, toPrecision() controls total significant digits.

2. How to round a number to the nearest integer in JavaScript?
   → Math.round(number)

3. How to generate a number between 1 and 100 randomly?
   → Math.floor(Math.random() * 100) + 1

4. What’s the output of Math.floor(Math.random() * 10) + 1?
   → A random number between 1 and 10.

5. What’s the difference between Math.floor() and Math.trunc()?
   → floor() always rounds down, trunc() removes the decimal part (like parseInt()).

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🧠 Homework Practice

1. Try these and predict results:

    console.log((12345.6789).toLocaleString());
    console.log((12345.6789).toFixed(2));
    console.log((12345.6789).toPrecision(6));
   

2. Generate:

   • Random number between 50 and 100

   • Round 3.14159 to 2 decimal places

   • Find max and min of [13, 7, 21, 4, 9]

3. Bonus Challenge:

   • Build a function rollDice() that returns a number from 1 to 6.

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📎 GitHub Repo

🔗 Day 6 Code on GitHub