I wonder if ours will be the last generation to be able to do mental arithmetic? I remember the older DDs pleading with me not to give in to youngest's request for a calculator when she was still in primary school asthey said she would never be able to do arighmetic any other way. I wouldn't say they are necessarily the greatest at it though, althugh eldest is now retraining as a Secondary Maths teacher)
Our mathe teacher used to reel off a string of numbers interspersed with "plus", "minus" ,"times", "divided by", (even "squared") and then stop and as you said, pick on someone for the answer - so woe betide anybody who lost the thread!