The reciprocal of the final value coefficient of annuity is called the sinking fund coefficient. According to relevant data, the reciprocal of the sinking fund coefficient and the final value coefficient in ordinary annuity is the sinking fund coefficient, that is, the sinking fund coefficient and the final value coefficient of annuity are reciprocal. The final value coefficient of annuity refers to the sum of principal and interest of equal income or expenditure at the end of each period.