Let be the Principal (initial investment), be the annual compounded rate, the ``nominal rate,''
be the number of times Interest is compounded per year (i.e., the year is divided into Conversion
Periods), and be the number of years (the ``term''). The Interest rate per Conversion
Period is then

(1) |

(2) |

(3) |

(4) |

The time required for a given Principal to double (assuming Conversion Period) is given by solving

(5) |

(6) |

(7) |

**References**

Kellison, S. G. *The Theory of Interest, 2nd ed.* Burr Ridge, IL: Richard D. Irwin, pp. 14-16, 1991.

Milanfar, P. ``A Persian Folk Method of Figuring Interest.'' *Math. Mag.* **69**, 376, 1996.

© 1996-9

1999-05-26