Calculation. Summary: This is the calculation used for figuring the yield to maturity of bonds and coupons purchased after 1984. This calculation can only be used if the period from purchase to maturity can be divided exactly into full accrual periods. To calculate: n multiplied by ((s.r.p. divided by a.p.) raised to the (1 divided by m) power minus 1): where: n is the number of accrual periods in one year, s.r.p. is the stated redemption price at maturity; a.p. is the acquisition price; and m is number of full accrual periods from purchase to maturity.