Children’s, would’ve been in print by 1970’s.
A boy is facing the challenge of how to get to the top of a castle. There is some discussion that he cannot jump there in one go. He eventually solves the problem by climbing to the top of the castle, one step at a time.
I believe this is “The Big Jump and Other Stories” by Benjamin Elkin, I really liked this one when I was young.
Phil, thanks so much! I’d forgotten to check back until now, and am so surprised someone was able to pick this from such skimpy detail. You’re a star. 🙂