Sinking fund is the inverse operation of ordinary annuity's final value formula, and the capital recovery and the present value of ordinary annuity are the inverse operations. If you know the final value, you can calculate the annual receipt and payment amount, that is, you can calculate the sinking fund. If the present value is known, calculate the annual income and expenditure, that is, the annual capital recovery.

For example, if someone wants to pay off 10000 five years from now, how much do they need to save at the end of each year from this year? This is the known final value, that is, the amount of the annuity after 5 years is 10000, which is the calculation of the sinking fund.

If the loan is 10000 now, it will be repaid five years from this year, and how much will it be repaid at the end of each year? This is the known present value of 10000 yuan. Seeking an annuity is the calculation of fund recovery.