Haruki and Minami is trying "100-masu keisan."
This is a kind of training for math calculation.
It was made by 11 by 11 row and columns.
One row and one column have the number from 1 to 10 at random.
They fill the 100 numbers of the result for addition or subtraction between rows and column at each blank.
I count the time of their calculation, and they compete against one another for that time.
It might increase their motivation for learning.
Their dairy routine study.