Generally, the airlines only require you to have the appropriate licence for job ie. a frozen or unfrozen ATPL. The bits that land you the job are the extras such as life skills, presentability, general educational background and being the sort of person that someone can sit next to for hours on end. But to get to that position, you will have to have a good grasp of basic maths and English. Your basic arithmetic should be pretty good because you will need this as you fly, the better your maths the better you will do. As BJ said, no rocket science just sine, cosine type trig stuff, fractions and general maths). It also pays to have a good grasp of English and it will be useful to be fluent in the language of the country of the airline that employs you. There is nothing worse than having locals discussing things that affect you or your fate in earshot and you not having a clue what they are saying.
PM