Even I don’t “know” how many “R”s there are in “strawberry”. I don’t keep that information in my brain. What I do keep is the spelling of the word “strawberry” and the skill of being able to count so that I can derive the answer to that question anytime I need.
For many words I can't say the number of each letters but I only have an abstract memory of how they look so when I write say "strawbery" I just realize it looks odd and correct it.