The present value factor for an annuity of n years is equal to the sum of the individual, single sum, present value factors for each of the n years. Therefore, the difference between the present value annuity factors for n and n − 1 years is equal to the present value factor of a single sum to be received at the end of the nth year. Therefore, the PV annuity factor for Year 5 should not be subtracted from Year 6 to find the PV factor of a single sum at Year 5.