Mental math is a skill people practice on a daily basis, often subconsciously, which involves doing calculations in your head. In mental math, you don't have to write down elaborate details concerning the variables involved.
Children are usually encouraged to learn mental math skills early in school, because being good at mental calculations can make a person successful in many other fields. Please note that even if being good at mental math does not necessarily signify high intelligence, people usually think it does, and that perception can help you obtain opportunities for advanced study or career development.
Mental math proficiency is not just good for academic pursuits but also helps make life easier overall. This book dives deep into the mechanics of mental math and provides examples that will help the reader build mental math proficiency quickly.