The order of operations is known as BODMAS. We can also define a set by its properties such as xx0 which means the set of all xs such that x is greater than 0 see Set-Builder Notation to learn more. It is actually really simple as others have said it means that a function lets say f maps A to B that is for an element in the set A you apply some rule to it then you get an element from the set B.
Angle brackets are used in group theory and commutative algebra to specify group presentations and to denote the subgroup or ideal generated by a collection of elements.
That is whichever A and B are A B is equivalent with A B or A B. We use the apostrophe to denote the complement of a set. X is a natural number x 10 If youre going to be technical you can use full set-builder notation to express the above mathematical set. Some authors see an apostrophe usually read as prime when its a mathematical symbol applied to a set to mean set complement meaning all elements of some larger ambient set which are not in.