
Re: Glorified calculators
To be strictly honest about this, mental arithmetic when done at speed in a challenging environment is difficult and takes a lot of practice to become good at. It is a really good example of a task that should be farmed out to a computer as rapidly as possible. I speak from experience here having been a bookmaker's clerk in my youth.
Adding up columns of numbers rapidly is very different from school-taught arithmetic. Out in the bookie world you add the big bits first and the smaller bits after and you don't fuss if you slightly over-estimate the take-out figures on any one horse, nor under-estimate the total cash taken on that race (the field money). The idea is to take more money in total than is paid out in any eventuality but to do that you need to know how much you've taken and how much each horse will cost if it wins.
A good clerk going flat out can just about keep up with the take-outs on most horses in a biggish race but will need occasional pauses to tot up the field money and otherwise square things up. A computer with the power of a modern smartwatch will do all of that and run a couple of displays into the bargain, AND trade off money to a remote betting exchange. Computers are GOOD at arithmetic, humans are not, and getting upset at this natural difference is basically stupid.