I want to improve my mental calculation skills, but there are so many different methods, e. g., flash anzan, Trachtenberg …
I am not quite sure, which method I should choose. I was hoping, that someone could help me.
I will use the method manly in everyday life and for work. That means, that I just need addition, subtraction, multiplication and division. The numbers will not be that big (for addition/subtraction -> max. six-digit numbers, for multiplication/division -> max. four-digit numbers), but I need a method, that works with decimal places.
Do you have a tip, which method is most suitable?