It's strictly math, so you could work up most any score you desire, see
below for explanation.
Flesch-Kincaid Grade Level test
This test rates text on a U.S. school grade level. For example, a score
of 8.0 means that an eighth grader can understand the document. For most
documents, aim for a score of approximately 7.0 to 8.0.
The formula for the Flesch-Kincaid Grade Level score is:
(.39 x ASL) + (11.8 x ASW) – 15.59
ASL = average sentence length (the number of words divided by the number
ASW = average number of syllables per word (the number of syllables
divided by the number of words)