The division symbol was causing confusion as it appears to be region depending.
It can now be selected in the main menu
Try to solve the math based puzzles while keeping these rules in mind...
The math for each group should be correct.
A value can not reappear in the same row.
A value can not reappear in the same column.
Groups are surrounded/marked by black lines.
More details and an example on how to solve a puzzle is added inside the app's info screen.
Have fun!