The name rational number is worth mentioning. The name "rational number" is puzzling, and rational numbers are no more "reasonable" than other numbers. Actually, it seems to be a translation error. The word rational number comes from the west and is rational in English, but rational usually means "rational". Modern China's translation of western scientific works was misinformed according to the Japanese translation method. Translated into "rational number". However, this word originated from ancient Greece, and its English root is ratio, which means ratio (the root here is English and the Greek meaning is the same). So the meaning of this word is also very clear, that is, the ratio of integers. In contrast, "irrational number" is a number that cannot be accurately expressed as the ratio of two integers, but it is not unreasonable.