Credit Card Number Generator

Understanding Credit Card Number Generation

Credit card numbers follow specific mathematical patterns and validation algorithms that ensure their structural integrity. The most important of these is the Luhn algorithm, also known as the “modulus 10” algorithm, which provides a checksum validation for credit card numbers. This tool generates mathematically valid test numbers that pass Luhn validation, making them suitable for software testing environments where realistic but non-functional card numbers are needed.

Credit Card Number Structure

The Luhn Algorithm

Testing Applications

Algorithm Implementation

function validateLuhn(cardNumber) {
    const digits = cardNumber.split('').map(Number);
    let sum = 0;
    let isEven = false;

    for (let i = digits.length - 1; i >= 0; i--) {
        let digit = digits[i];
        
        if (isEven) {
            digit *= 2;
            if (digit > 9) {
                digit -= 9;
            }
        }
        
        sum += digit;
        isEven = !isEven;
    }

    return sum % 10 === 0;
}

function generateCheckDigit(partialNumber) {
    const sum = calculateSum(partialNumber);
    const remainder = sum % 10;
    return remainder === 0 ? 0 : 10 - remainder;
}

def validate_luhn(card_number):
    digits = [int(d) for d in card_number]
    checksum = 0
    is_even = False
    
    for digit in reversed(digits):
        if is_even:
            digit *= 2
            if digit > 9:
                digit -= 9
        checksum += digit
        is_even = not is_even
    
    return checksum % 10 == 0

def generate_check_digit(partial_number):
    total = calculate_sum(partial_number)
    remainder = total % 10
    return 0 if remainder == 0 else 10 - remainder

Security and Legal Considerations

Common Testing Scenarios

Industry Standards and Compliance

Related Mathematical Tools