The recommended environment for using Online-soroban.com is as follows.
● Macintosh
 · Safari 5.1 and above
 ● Windows
 · Internet Explorer 9.0 or later
 · Firefox latest version
 · Chrome latest edition
 ● Tablet
  · Android OS 4.0 or later
  · IOS 7.0 or higher
  * Standard browser of each installed terminal
 ● Smartphone
We does not recommend using smartphones to study the courses in Online Soroban