I bought 2 and 3 subjects individually and then bought the entire course! I passed the 2nd Information Processing Engineer exam with a good score, so I was confident in preparing for the Big Data Analysis Engineer written exam, but I was stuck in the wall from the 2nd subject, but after listening to the lecture, I was able to get my mind started. I have never spent money on a written exam for a qualification, but the explanations were good, and after each section, I reviewed the past questions right away, so I remembered them well, so I bought the package again that includes subjects 1 and 4!! I will persevere and definitely pass!!