Another interesting observation is that my ability to do arithmetic calculations is radically better when I speak Russian. I can talk and calculate without slowing down much. When I speak English I sound like almost math-illiterate person since my ability to do calculations in English speaking state is very limited. This is obviously because I learned my math in Russian school. I conclude that for me and likely for majority of humans calculations are done using in large extent a speech processor in the brain. I literally use verbal phrases to add and multiply. We have been trained to do calculations aloud, that is how we do arithmetic's. Arithmetically talented people, who do it way faster and with fewer errors, are very likely using other ways of doing calculations. I hope this understanding will help you understand how our mind works and when we are unable to do simple math in your presence, understand that we may be substantially better in math in home environment. I could also project that switching from our decimal numbering system to your duodecimal (12-based) and sexagesimal (60-based) numbering systems our adults would likely have to use artificial calculators or some minor brain reprogramming for translation between our numbering systems. Our children would need to learn your numbering systems and arithmetic in early age.