Edit: it appears that this is not exclusive to ADHD.
Posting this meme stemmed from my own efforts to explain my thought process when doing math and how it is similar to other people with ADHD doing math, while being different from every neurotypical person I'd talked to on the same subject.
While I didn't make the meme itself, instead finding it in my saves and wanting to share, I did accidentally spread misinformation that I had only backed up with personal anecdotal evidence.
I'll leave this up just so people can see the explanation below but this appears to not be ADHD related and just due to different people doing math in their heads differently...
I always tell my children that Maths is finding the best way to cheat at a problem. Don't solve the hard problem. Solve the easy one that's kind of like the hard problem and then find the difference.
And judging by the school material that's how they're supposed to do it. But either the teachers aren't explaining it that way or the kids aren't listening.