Challenge Day 6

Odd, Even, or Special?

June 15, 2025

JavaScript, Conditions, Logic

Syifa Fauziyah Arizal

Today's challenge focuses on number classification with layered logic to sharpen coding reasoning skills, including checking for odd, even, and multiples of 10.

Challenge Goals

Practice nested conditions (if, else if, else)
Understand odd, even, and multiple concepts
Add input validation & more human-friendly output

Program Description

User inputs a number
Program checks if the number is:
- ✅ Odd
- ✅ Even
- 🎉 Multiple of 10 (shows special message)
Output includes emojis to make it more expressive 😄

Example Output


Enter a number: 27
➡️ 27 is an odd number 🔹

Enter a number: 44
➡️ 44 is an even number 🔸

Enter a number: 30
🎉 30 is an even number & multiple of 10!

Tools & Concepts

prompt() and parseInt() to get user input
isNaN() for input validation
if and else if for conditional logic
% (modulus) operator to check odd/even/multiples

Basic Implementation

Initial Version


const input = parseInt(prompt("Enter a number:"));

if (isNaN(input)) {
    console.log("Please enter a valid number 😅");
} else if (input % 2 === 0) {
    console.log("This is an even number 👍");
} else {
    console.log("This is an odd number 👌");
}

Adding: Multiple of 10

Enhanced Condition


else if (input % 10 === 0 && input % 2 === 0)

Full Code Version 1:

With Special Case


const input = parseInt(prompt("Enter a number:"));

if (isNaN(input)) {
    console.log("Please enter a valid number 😅"); 
} else if (input % 10 === 0 && input % 2 === 0) {
    console.log("🎉 This is an even number and multiple of 10!");
} else if (input % 2 === 0) {
    console.log("🔸 This is an even number!");
} else {
    console.log("🔹 This is an odd number!");
}

Bonus Challenge: Loop Version

Interactive Version


let input;

while (true) {
    input = prompt("Enter a number (type 'exit' to quit)");

    if (input === "exit") {
        console.log("Goodbye! 👋");
        break;
    }

    const number = parseFloat(input);

    if (isNaN(number)) {
        console.log("❌ Please enter a valid number 😅"); 
    } else if (number % 10 === 0 && number % 2 === 0) {
        console.log("🎊 This is an even number and multiple of 10!");
    } else if (number % 2 === 0) {
        console.log("🔸 This is an even number!");
    } else {
        console.log("🔹 This is an odd number!");
    }
}

Addition: Check Negative Numbers

Final Code:

Complete Solution


let input;

while (true) {
    input = prompt("Enter a number (type 'exit' to quit)");

    if (input === "exit") {
        console.log("Goodbye! 👋");
        break;
    }

    const number = parseFloat(input);

    if (isNaN(number)) {
        console.log("❌ Please enter a valid number 😅"); 
    } else if (number < 0) {
        console.log("📉 This is a negative number...");
    } else if (number % 10 === 0 && number % 2 === 0) {
        console.log("🎊 This is an even number and multiple of 10!");
    } else if (number % 2 === 0) {
        console.log("🔸 This is an even number!");
    } else {
        console.log("🔹 This is an odd number!");
    }
}