I was 11 in sixth, and some of this stuff kept going into junior high. So, yeah, about the same age.
Mind you, none of this was good. Yes, it kept me from being bored, but it was a symptom of a failure on the school's part. I should have been in an accelerated learning program, but the school didn't have the resources to accommodate that.
So I slacked off and breezed through. And got used to breezing through, all the way through high school, such that by the time I started college I had absolutely no idea how to study. I'd never had to do it before.