If I didn't have access to my numerical analysis books and no connection to the internet, and a no pressure to optimize the function, it would look something like this.

nAnswer = sr(100,1,100)
? "THE ANSWER:", nAnswer

FUNCTION sr(pOrig,pLower,pUpper)
* attempt to determine the square root by dividing the interval
? pOrig, pLower, pUpper
WAIT
nMiddle = ((pUpper - pLower) / 2) + pLower

DO CASE
	CASE pOrig = nMiddle*nMiddle 
		RETURN nMiddle
	CASE pOrig > nMiddle*nMiddle
		RETURN sr(pOrig,nMiddle,pUpper)
	CASE pOrig < nMiddle*nMiddle
		RETURN sr(pOrig,pLower,nMiddle)
	OTHERWISE
		? "ERROR: an impossible result!"
		RETURN 0
ENDCASE
RETURN

>Write a function to calculate the square root of a number to a given number of decimal places. (Yes. I know, VFP has the SQRT function, but what would you do without it?)