I mean, what's the point of drilling stupid sums if you'll hardly ever need it in your life? "Hardly ever"? So when checking the restaurant bill, the change at

I mean, what's the point of drilling stupid sums if you'll hardly ever need it in your life? "Hardly ever"? So when checking the restaurant bill, the change at the grocery shop, the tax return, a bank investment proposal, the costs of building/renovating a house, the time left for a mortgage, do you always use a calculator?