The mnemonic is please excuse my dear ant sally for parenthesis exponential multiplication division addition subtraction.
Where people get tripped up is that the MD and AS pieces of PEMDAS has equal priority and when there is a conflict you always go left to right.
6/2*(1+2) parenthesis first
6/2*3 multiplication and division, left to right
3*3 multiplication.
9
The reason this is so hard for people, is because these rules are not being followed by everyone consistently.
And these errors exist even in the algebra engines that come with some software packages because yes even computer programmers can be idiots and use the wrong algorithm or feed a stack from the wrong side making a fifo instead of a lifo.
With this mathematical communication issue dealt with, we can move on to more important topics, cleansing the gene pool, removing evil elements, because yes, removal of a negative is the same as positive in terms of virtue.
https://www.youtube.com/watch?v=QWBV73yBleU