The total score looks right -
DD took it twice in second grade and once in third.
It wraps the performance on those three subtests for a composite of sorts. From the different instances of the scores I've seen, it can be brought up to the 95%ile with 1 high score. Social studies and science, if given, are not part of the total battery.
There are 25-30 questions per test.
From the bits I've seen and pieced together, the second grade 99%ile in math is an artificial score - more than 1% get them all right, so the statistics would actually lead it to be a 94-97 depending on the year and test version.
The reading and language arts was not well aligned to the way that reading and language arts were taught in our schools. Reading was a focus on reading comprehension, but generally focusing on making inferences as much as understanding content. LA has a huge focus on spelling and grammar at this level (commas and capitalization).
Because of that, it's not surprising if the reading and LA were lower than you might have expected, or otherwise out of sync with his math score.
In second and third grades, there are also a lot of parts of the test that were given orally, with the entire class moving through the test together. This drove my daughter nuts, and once the pressure was off (our schools use it for gifted admission which she hit in second grade) then she did not do well because of irritation at the format.
