Because the average life expectancy of people over 6 years old in China is 139 months, it is divided by 139.

the basic pension is paid by the state, and the monthly calculation and payment standard of personal account pension is the total storage amount of personal account divided by 139(139 is the calculation and payment coefficient of new rural insurance pension. This calculation method is to distribute the personal account funds for an average of 139 months).

the basic old-age insurance premium is shared by the enterprise and the individual employees: the enterprise pays a certain percentage of the total average monthly salary of its employees in the previous year (19% in Beijing, which may be different in other cities), and the individual employees pay a certain percentage of their average monthly salary in the previous year (generally 8%).

individual industrial and commercial households in cities and towns, flexible employees and laid-off workers from state-owned enterprises who participate in the basic old-age insurance in their personal capacity will pay the basic old-age insurance premium at the rate of 2% based on the average social wage in the province where they live last year, and all of them will be borne by themselves.

Social Insurance Law of the People's Republic of China

Article 11 The basic old-age insurance shall combine social pooling with individual accounts. The basic old-age insurance fund consists of employer and individual contributions and government subsidies.

article 12 an employer shall pay the basic old-age insurance premium in proportion to the total wages of its employees as stipulated by the state and record it in the basic old-age insurance pooling fund. Employees shall pay the basic old-age insurance premium according to the proportion of their wages stipulated by the state and record it in their personal accounts. Individual industrial and commercial households without employees, part-time employees who have not participated in the basic old-age insurance in the employer and other flexible employees who have participated in the basic old-age insurance shall pay the basic old-age insurance premium in accordance with state regulations and record it in the basic old-age insurance pooling fund and individual account respectively.

article 13 before employees of state-owned enterprises and institutions participate in the basic old-age insurance, the basic old-age insurance premiums that should be paid during the period of deemed payment shall be borne by the government. When the basic old-age insurance fund is under-paid, the government gives subsidies.