DISC

DISC(settlement, maturity, price, redemption [,basis])

Returns the interest rate (or discount rate) for a security held to maturity.

settlement	The settlement date of the security.
maturity	The maturity date of the security.
price	The security's price per $100 face value.
redemption	The security's redemption value per $100 face value.
basis	(Optional) The type of day counting to use: 0 = 30/360 (default) 1 = Actual/Actual 2 = Actual/360 3 = Actual/365 4 = 30E/360

REMARKS

* This interest rate is often called the discount rate.
* The "settlement" is the date a buyer purchases a coupon, such as a bond.
* The "maturity" is the date when the security expires.
* Dates must be entered as text strings within quotation marks or as serial numbers.
* If "settlement" is not an integer, it is truncated.
* If "settlement" >= "maturity", then #NUM! is returned.
* If "settlement" is not a valid date, then #NUM! is returned.
* If "maturity" is not an integer, it is truncated.
* If "maturity" is not a valid date, then #NUM! is returned.
* If "pr" <= 0, then #NUM! is returned.
* If "redemption" <= 0, then #NUM! is returned.
* If "basis" is left blank, then 0 is used.
* If "basis" is not an integer, it is truncated.
* If "basis" < 0, then #NUM! is returned.
* If "basis" > 4, then #NUM! is returned.
* This is similar to the INTRATE function.
* For the Microsoft documentation refer to support.microsoft.com
* For the Google documentation refer to support.google.com

	A
1	=DISC("31/3/2011", "30/9/2011", 97, 100, 0) = 6.00%
2	=DISC("2/15/1998", "6/10/1998", 97.975, 100, 2) = #VALUE!

1 - What would the interest rate be if you bought something at a price of $97 with a settlement date of 31 Mar 2011 and then sold it at a price of $100 on a maturity date of 30 Sept 2011. Assuming a day count of 30/360.