Singles and doubles can also refer to gender. The distinction between men and women is single and double, not only literally, but also the division between the two sexes. In society, they each play an important role and play different roles. Men are given the responsibility of supporting their families and ensuring their livelihood, while women pay more attention to family maintenance and children's education, and play the role of inheriting family culture. Therefore, the visual differentiation of single and double also reflects the difference of social roles.
Singles and pairs can also refer to the last digit of the ID number. In China, there is a geomantic culture, which holds that people whose last ID number is singular are more likely to bring good luck, while even numbers are the opposite. It is said that odd numbers are easy to bring good luck and get rich, while even numbers mean bad luck and easy to get into trouble. Although there is no scientific basis for this statement, there are still some people who will inherit this belief and choose to pay attention to odd and even numbers in buying a house, getting married and falling in love.