In elementary mathematics instruction four types of calculation should be distinguished from each
other: mental calculation, informal strategies, written algorithms, and the use of calculators. Each of these
methods is connected with a specific degree of importance, but written algorithms traditionally are given priority
over the other ones. The present paper pleads for a new reflection and reexamination of the four types that takes
the specific features, intentions and strengths of each method into account. The essential suggestion is to reduce
written algorithms in favor of mental calculation and informal strategies. This point of view is both theoretically
founded and illustrated by means of typical examples.
From Günter Krauthausen in the text Kopfrechnen, halbschriftliches Rechnen, schriftliche Normalverfahren, Taschenrechner (1993)