write a function to receive a whole number and return the max digit avoid using var

public static int GetMaxDigit(int num)
{
    int max = 0;
    while (num > 0)
    {
        int digit = num % 10;
        if (digit > max)
        {
            max = digit;
        }
        num = num / 10;
    }
    return max;
}