The explanation was not smooth and I kept thinking that the lecture was prepared without any prior preparation. He kept saying, "Just a moment, I'm sorry," and in his own example using the round function, he said, "Why is the value automatically dropped to a decimal point? This is unnecessary," and in the part where the output data he wrote was different from the value that came out, he said, "Why is this? Anyway, let's move on," which lowered my trust. Even if the value is exact and the round function is not needed, if he put it out as an example of use, shouldn't he have modified the example value so that it could be used? I think he should have modified/reflected that before putting it out as a lecture. There were many other parts like this. The lecture content and explanation were based only on English, which was inconvenient, and even though it was a paid lecture and not a free lecture, the quality of the lecture was not as good as a free lecture. The only good thing was that the lecture part was divided into sections, so I could skip all the parts I knew.