Complex sentence: He progressed through mathematics and the sciences at a quick pace, having his first published article at 13, despite this he has apparently received no formal higher qualifications as he was already working in the mathematics field by the time he left High School.
Split into simpler sentences: He progressed through mathematics and the sciences at a quick pace, having his first published article at 13. Despite this he has apparently received no formal higher qualifications as he was already working in the mathematics field by the time he left high school.