This is japanese right brain training called Flash Anzan.
You add all numbers popping up one after another.
This mental arithmetic application will make you able to perform hundreds calculations a minute.
If you fall into a slump, you should remember following words.
Don't think. FEEL!(Bruce Lee)
Speed range (4.0sec - 0.15sec)
Number of Digits (1 - 5)
Number of calculation times (5 - 100)
Including negative number or not
Fix number of digits or not
To save the percentage of questions answered correctly
To retry the previous question
To start again where you left off