The importance of mental computation has been identified by a considerable body of research.
It has been found that nearly 80% of all calculations by adults are carried out mentally, and that frequently estimation is sufficient.
Approaches to calculation in school should reflect the demands of everyday life, as explained in the article Put Mental Computation First? on the AAMT website.
Research also indicates that an emphasis on mental computation can improve students' development of number, while an early introduction to formal written methods can harm it.
The Australian Curriculum: Mathematics includes mental strategies as well as written and technology-based methods.
Mental strategies provide an important window into students' understanding of number.
