def print_number(n):
    """ return numbers as string with space seperating every set of 3 digits.
    >>> print_number(12)
    '12'
    >>> print_number(1234)
    '1 234'
    >>> print_number(1234567)
    '1 234 567'
    >>> print_number(1.00)
    '1'
    >>> print_number(1.99)
    '1.99'
    """
    return '{:,}'.format(n).replace(',', ' ').rstrip('0').rstrip('.')

doctest.testmod()