I'm sure people would do that in many cases (counting in their head). But the point is in a shop without a computer, a calculator is de rigueur if it is accessi

I'm sure people would do that in many cases (counting in their head). But the point is in a shop without a computer, a calculator is de rigueur if it is accessible and affordable; if nothing else than for accounting, stock taking, book keeping etc. And as mentioned, calculator I have seen being used as a communication mechanism (You ask what's price? Seller taps on the calculator and shoves it under your nose without uttering a single word : 72.50)