You have already given an example of when you would use 'such calculations'.

If you have 500 loaves, then another 450 and you need to divide it between 5 supermarkets - how many does each supermarket get.

The calculation is (500+450)/9

BODMAS is taught to 10/11 year olds. Has been around since 1923, but formally became part of the National Curriculum in 1988. You spent your maths lessons torturing your teacher - I suppose that is OK as well.