Attention Distribution Test 49

It is a simple app to measure your basic attention by looking for a number that has been placed at random from 0.
By repetition training, you can expect an increase in the score! 

for the following people
-want to improve powers of observation.
-want to improve ability to concentrate.
-want to be a professional gamer.
-look for the examination preparation.

including following games
-4x4 16cells.(casual!)
-5x5 25cells.
-6x6 36cells.
-7x7 49cells.(standard!)