How long will it take

[Red over White]

I'm trying to establish how many days it will take the principal sum {PS} (say £1,000) to increase by £2 (but not exceed £1,002) when the interest rate {IR} is 5.50%. I know the answer {AN} is 13, because I have set up a formula using PS, IR, AN along with '/365'. The formula reads =K27*K29/365*K31 {or PS*IR/365*AN}. However, I have not been able to reverse engineer the formula to get to a figure close to 13, let alone put a limiter of £2.00 into the mix.

Any suggestions ...

 

[Anthony47]

A not so smart formula:

=MAX(IF(K27*K29/365*ROW(A1:A100)<=2,ROW(A1:A100),0))

 

[Red over White]

Thanks Anthony47

 

[Dave Patton]

T202312a.xlsm
	B	C
1	Principal	1,000.00
2	Rate	5.50%
3	FV	1,002.00
4	Nper	13.26
5
9b

Cell Formulas
Range	Formula
C4	C4	=NPER(C2/365,0,-C1,C3,0)

 

[AhoyNC]

Formula to calculate number of days
days=ln(Future Value/Present Value)/ln(1+rate/365)
I get an answer of 14.4 days.
See example below.

Book1
	A	B	C	D
1	principal	1000
2	Future Value	1002
3	Yearly Rate	5.05%
4
5	number days=	ln(FV/PV)/ln(1+rate/365)
6	Days =	14.44
7
8	Check
9	Future Value	$1,002.00
10
Sheet2

Cell Formulas
Range	Formula
B6	B6	=LN(B2/B1)/LN(1+B3/365)
B9	B9	=FV(B3/365,B6,,-B1)

 

[AhoyNC]

I just noticed I used the wrong rate in my post #5 above (should have been 5.5%).
I would also use the Excel formula that Dave Patton has in his post above.