Is this still a relevant skill-set to be good at these days? I feel like it&#x27;s a bit like writing cursive or being able to have good handwriting in general. It&#x27;s just not that useful anymore unless you&#x27;re in very specialized fields that require you to be good at mental math and even then how many situations are you in where you&#x27;re put on the spot that you have to mentally solve something? There&#x27;s probably more useful things to keep in your brain than these types of tricks.<p>I don&#x27;t mean to be so negative though. I certainly think it&#x27;s very fascinating and interesting just from a pure mathematical perspective. However we also have to consider the utilitarian perspective when asking &quot;why&quot; many people aren&#x27;t good at something like this anymore.