This book is intended for people who want to keep their minds in good shape. For all ages. Mathematics is the simplest and it is easy to learn by example.

Fatal error: Uncaught Error: Call to a member function fetch_row() on false in /home/user/web/тумба.онлайн/private/versions/ver_5/pages/books_single.php:285 Stack trace: #0 /home/user/web/тумба.онлайн/private/versions/ver_5.php(577): include() #1 /home/user/web/тумба.онлайн/public_html/index.php(200): include('...') #2 {main} thrown in /home/user/web/тумба.онлайн/private/versions/ver_5/pages/books_single.php on line 285