(I suspect that there are other questions asking for math books accessible to middle school students but I couldn't find them. )
I am looking for math books for middle school students who find math taught in class easy. Assuming that they have knowledge of arithmetic (basic operations on numbers), some geometry and algebra what books could challenge them?
Arithmetic- Addition, subtraction, multiplication, division. Geometry- What polygons are, practical geometry involving the Pythagoras theorem, finding areas with very little experience writing proofs. Algebra- Solving linear equations in one variable.
I was thinking number theory, but I am not sure if there are books that are accessible to them and also interesting enough.