SAT is of Reasoning Paper and also Subject paper. The subject paper depends on the subject you want to take up the admission in your Undergraduate programme abroad. SAT exam is for 3 hours and an additional 50 minutes if you also have opted for an essay. Or else it is going to be Mathematics section and Evidence Based Reading and Writing. The higher the SAT score, better are the chances for top Colleges of the US. Because this is a pen and paper mode exam, you have to be real careful. You cannot back to one section and cannot swap between sections. Let's say if you have finished Math section earlier than the allotted time, you cannot move to the next section. And if the time allotted is for Math section, you cannot go to Reading and Writing section.
Maths is divided in to 2 sets of questions where in one can be attempted using a calculator and the other without a calculator. The one with calculator has 20 questions for 25 minutes and the set with calculator has 38 questions with a time limit of 55 minutes. The Evidenced based reading test has 52 questions with a time limit of 65 minutes minimum and Writing and Language test has 44 questions with a minimum time limit of 35 minutes.
For Maths session, a set of formulae and references are provided at the beginning of the test and the questions come from Heart of Algebra, Problem Solving and Data Analysis and Passport to Advance Math. You may also have to practise topics like Area and Volume, Coordinate Geometry and Basic Trigonometry.
Under Reading Test, one literary passage from American or International work of fiction like short stories or novels. One passage from US Founding documents or Great Global Conversation covering topics like freedom, justice and human dignity. Other topics might be on Economics, Psychology, Sociology, etc. 2 passages might be from Work of science. The questions asked in this section are Information and Ideas, Rhetoric and Synthesis and we have to draw conclusions and make connections between the passages.
Under Writing and Language test, topics explored are career, science, humanities, history and social science. Please practise as many as sample papers you can.