def normalise_version_str(version_num, normal_len):
    """Normalise the length of the version string by adding .0 at the end

    >>> normalise_version_str(1.0, 3)
    1.0.0

    >>> normalise_version_str(1.0.0, 4)
    1.0.0.0
    """
    version_num_parts = len(version_num.split('.'))
    if version_num_parts < normal_len:
        for i in range(version_num_parts, normal_len):
            version_num = version_num + '.0'
    return version_num
