Multiply numbers

BigNum multiply_numbers(BigNum& num1, BigNum& num2)
{
    BigNum result{};

    if (num1.base == num2.base)
    {
        result.base = num1.base;
    }
    else
    {
        return result;
    }

    auto it1 = num1.number.rbegin();
    uint64_t tens = 0;

    while (it1 != num1.number.rend())
    {
        auto it2 = num2.number.rbegin();

        BigNum number{};
        number.base = num1.base;

        uint64_t base = num1.base;
        uint64_t digit = 0;
        uint64_t carry = 0;

        while (it2 != num2.number.rend())
        {
            auto tmp = *it1 * *it2 + carry;

            digit = tmp % base;
            carry = tmp / base;

            number.number.push_back(digit);

            it2++;
        }

        if (carry != 0)
        {
            number.number.push_back(carry);
        }

        std::reverse(number.number.begin(), number.number.end());

        for (uint64_t i = 0; i < tens; i++)
        {
            number.number.push_back(0);
        }

        tens++;

        result = add_numbers(result, number);

        it1++;
    }

    return result;
}