Pincode validate

        const regions = {
    1: "Delhi",
    2: "Uttar Pradesh & Uttarakhand",
    3: "Rajasthan & Gujarat",
    4: "Maharashtra",
    5: "Andhra Pradesh & Telangana",
    6: "Tamil Nadu & Kerala",
    7: "West Bengal & North East",
    8: "Bihar & Jharkhand",
    9: "Army Postal Service"
};

const sub_regions = {
    11: "Delhi Region",
    40: "Mumbai Region",
    60: "Chennai Region",
    70: "Kolkata Region"
};

const districts = {
    110: "Delhi",       111: "Delhi (North)",      112: "Delhi (South)",
    400: "Mumbai",      401: "Mumbai (Suburban)",   402: "Mumbai (West)",
    600: "Chennai",     601: "Tiruvallur",          602: "Kanchipuram",
    700: "Kolkata",     701: "Kolkata (North)",     702: "Kolkata (South)"
};

function getPincodeDetails(pincode) {
    if (!/^\d{6}$/.test(pincode)) {
        console.log("Invalid pincode. Enter exactly 6 digits.");
        return;
    }

    const num        = Number(pincode);
    const firstDigit = Math.floor(num / 100000);
    const firstTwo   = Math.floor(num / 10000);
    const firstThree = Math.floor(num / 1000);

    console.log("Region:     ", regions[firstDigit]   || "Unknown");
    console.log("Sub-region: ", sub_regions[firstTwo] || "Unknown");
    console.log("District:   ", districts[firstThree] || "Unknown");
}

getPincodeDetails(prompt("enter the number"))