Hello Bostonian.
The decimals mean how much he completed of that topic in percentage. For example, in integers, if it says 0.84, It means he has completed 84% of the topic of Integers. It doesn't mean he is scoring 84 percent. He got 83 percent in measurement, which surprised me, because you said the course was easy for him. Then you said his younger bro was doing some of it for him. First of all, how is he gonna learn if his younger bro is doing it, and second of all, why don't you just sign your younger one up for epgy too, even though it costs so much, I mean it looks like he really wants to do it... Anyway, my son did this, but the lessons were confusing and didn't offer much insight on the topic. He was really only doing the course for credit, so he could go to a higher class, more at his level. Even though the teaching was bad, he had no problem with it, as he had learned all the topics before.
Sorry for the long reply.
Sincerely,
HelperMom