なんだかよくわからない理論とか数式とかは小学生には難しすぎました。
調べようにも専門書は高くて、月300円のお小遣いじゃとても買えませんし、多分読んでも余計理解できなかったと思います(^^;)

All those rather unclear theories and formulas were just too difficult for a kid in elementary school to understand. Even if I'd want to look into them, specialty books were expensive, so there was no way I could buy them on a monthly allowance of ¥300, and even if I'd read them, I think I probably wouldn't have understood them at all. (^^;)