I'm trying to learn arithmetic from scratch again. Even though I can use it, I'm not sure if I can teach it to someone and I believe if you can't teach something properly, there might be loopholes in your understanding. Hence, I'm looking for a book that discusses various topics of arithmetic, like numbers (counting, fractions, integers, rational, real), numerals, place value number systems, addition, multiplication, division, etc very explicitly.
You might check out the OpenStax Prealgebra text. It seems to have much of what you’re looking for.
I have used this book to help me understand mathematics and prepare for my exams. It is helpful for all levels and the explanations are clear and friendly.