Which math and FP books are easy to learn?

Question

Books

I would like to ask those who know what books you can use to improve the skill of mathematics and functional programming. My current knowledge of mathematics is at the level of grade 9, so I would like a book that is not difficult to understand and interesting. Separately, I would like a book on FP, preferably if it contains examples, then in Lisp or Python, but not necessarily. Both are in Russian, I think my knowledge of English is still insufficient for such literature.
PS I know about SICP

Answer 1

Gödel, Escher, Bach: this endless garland. Hofstadter, 1979.