the thought process

if i told you 90% of what i write here is "solved" in my head before i post, would you believe me?
The complex equations of how ground water flows, i "see" clearly in my head, but to explain so others can understand it seems many times, difficult.
The why i reach the conclusion i do, is where i grasp.
i had this problem in High school and the teachers hated me.
The algeabreic concepts that fell into place so easily - the answers came with out a second thought.  Me reading a book or playing chess and they would call on me to see is they could catch me and they could not untill they asked me to go through the proof.  Writing down a proof systematically would show so many little errors that my mind, in an instant corrected.  A minus sign misplaced, addition of 1 + 1 = 3.  Writing down gave issue, but in my head i always had the correct answer.
so i stuggle with math that can not be explained easily to write it down, so you can understand and i make errors,  but the conclusions are , i believe correct.