Attempt the question, check the explanation, and continue with similar questions to build confidence before exams.
1, 6, 15, 20, 15, 6, 1
1, 5, 10, 10, 5, 1
1, 7, 21, 35, 35, 21, 7
1, 3, 3, 1
Continue with nearby questions to strengthen the same chapter concept while you still have the context fresh in mind.