To calculate your marks in the Combined Defence Services CDS exam from the CDS answer key, you can follow these steps: a) Download the CDS answer key: The CDS answer key is usually released by the Union Public Service Commission UPSC a few days after the exam is conducted. You can download the answer key from the UPSC's official website. B) Match your answers with the answer key: Compare your answers in the exam with the answers provided in the answer key. For each question, if your answer matches the answer provided in the key, mark it as correct. If your answer is different or if you have left the question unanswered, mark it as incorrect. C) Calculate the total number of correct and incorrect answers: Add up the number of correct answers and incorrect answers to get the total number of attempted questions. Make sure to deduct any negative marking for incorrect answers, as per the exam pattern. D) Calculate your marks: Use the marking scheme provided in the exam pattern to calculate your marks. For example, in the CDS exam, 1 mark is awarded for each correct answer, and 1/3rd of a mark is deducted for each incorrect answer. Multiply the total number of correct answers by 1 and the total number of incorrect answers by 1/3, and subtract the latter from the former to get your total marks. E) Cross-check with the cut-off: Finally, compare your calculated marks with the cut-off marksfor the respective exam and category to assess your chances of qualifying for the next stage. The cut-off marks may vary depending on factors such as the number of candidates, difficulty level of the exam, and availability of seats.