Children in China remember the multiplication table from 1 to 10 at grade 3, as part of the curriculum, as well as additions and subtractions with arbitrary number of digits.<p>Think of a piece of software where the hot paths get their result directly inlined for perf. Basic arithmetics occupy the &quot;hot path&quot; of your math curriculum until at least high school or beyond. This has a huge influence on reducing the amount of information you need to temporarily hold in your brain at once, leaving room for more important calculations such as exploring the solution space creatively, where one extra piece of information can make or break an insight.<p>Similarly, you can certainly look up a frequently used word in the dictionary every time if you need to. But you might as well memorize the definition once and for all. Now it&#x27;s a question of where to draw the line. For creative professions such as math&#x2F;engineering&#x2F;art, I&#x27;d definitely prefer hard-coding some calculations in my brain for the previously mentioned reason.