Speed Mental Calculation

This app is "flash anzan" so-called.
After the countdown, random number will be displayed by pressing the "Start"
button.
Please enter the anser to the sum of those numbers.

You can change the screen set-up, the number of digits, display seconds,
question count of randome numbers.
History of challenge list/graph can display in hisotry display screen.

In addition, you can set the font of the text to be displayed, size, color,
and background color.
Please use the easy-to-read settings.