For broadening his view, and sparking some fun and joy of maths, try "Humble Pi" by Matt Parker: https://www.goodreads.com/book/show/39074550-humble-pi https:/

For broadening his view, and sparking some fun and joy of maths, try "Humble Pi" by Matt Parker: https://www.goodreads.com/book/show/39074550-humble-pi https://www.goodreads.com/book/show/39074550-humble-pi