Taking the lead in this work are schools in Tongdaewon District, Pyongyang.

The District School for Teachers' In-service Training systematized the principles of mental arithmetic into various categories in line with the intellectual level and psychology of pupils. And it found out a way for the pupils to master the mental arithmetic in a short time before generalizing it among primary schools in the district.

In particular, Tongdaewon and Samma primary schools in the district created advanced teaching methods on the basis of the principles of mental arithmetic and conducted the extracurricular education among pupils with the methods for one hour every day.

As a result, the pupils' cogitative faculty was considerably improved in several months and the rate of honor pupils at the schools increased from 70 percent to 98 percent.

The introduction of mental arithmetic in teaching is helpful to improving the nation's general education.