Books 1, 2 and 6 are plane geometry, books 3 and 4 are what we now call trig, book 5 is on what we now call real numbers, books 7-9 are on integer number theory

Books 1, 2 and 6 are plane geometry, books 3 and 4 are what we now call trig, book 5 is on what we now call real numbers, books 7-9 are on integer number theory, book 10 is on irrationals, and books 11-13 are on solid geometry.