There is, if you use cash you just go back in to get the change and if using a card it will only actually take what was used. Basically just puts a hold on the account and finalizes at the end of the transaction.

No, he would have a very hard time explaining quantum mechanics to anyone because he doesn’t understand it.

I agree completely with the mixing of types but we can look at an SAE bolt and tell what size it is just as easily as you can look at a metric one. And maybe it’s bad manufacturing or some other type of industry standard but I have had many more metric bolts with a different sized head for a given shaft size than with SAE, like an M12 with anywhere from 17mm to 19mm head.