The number of NATA previous year papers you should solve for NATA exam preparation depends on various factors such as your level of knowledge, the time you have to prepare, and your individual learning style. However, as a general guideline, it is recommended that you solve at least 5-10 years of previous year papers to get a good understanding of the exam pattern, type of questions asked, and the level of difficulty. Solving previous year's papers will not only help you identify your weak areas but also improve your speed and accuracy in answering questions. It is also important to note that simply solving the papers is not enough; you should also analyze your mistakes and revise the concepts that you find challenging. Additionally, you can also take mock tests to further assess your preparation level and get a feel for the actual exam. Solving a sufficient number of NATA previous year papers is an essential part of your exam preparation strategy.