We had parents at the Catholic school our kids attended that used to argue with the principal about why their child should not have been in the 99th percentile because they didn't get any wrong answers. She had to explain carefully that their kids WERE the 100th, that 99% were BELOW them. Took them a bit to process that. ;o)
Makes me feel not so stupid for having thought the same thing in 3rd grade!
Mom always said the tests didn't mean anything anyway, they were just something the state required. She knew how we were doing, and didn't care if we were 99th% or 5th%.