Help with interest rate on a loan

[SpaceAgentX]

can anyone show me the arithmatic for calculating the interest rate on a loan when you don't know the loan term? Like say I get 1000$ for a TV at an 18% interest rate and I pay 50$ a month. How do I see how many months it will take? I want it to look like this 

---------------------------------------------------------------

Selling Price        =   1000.00

Down Payment         =      0.00

Amount of Loan       =   1000.00

Annual Interest Rate =      0.18

Monthly Payment      =     50.00

---------------------------------------------------------------

Pay #  Old Balance   Payment  Interest  To Balance  New Balance

-----  -----------   -------  --------  ----------  -----------

   1       1000.00     50.00     15.00       35.00       965.00

   2        965.00     50.00     14.48       35.52       929.48

…

…

  23         95.69     50.00      1.44       48.56        47.13

  24         47.13     47.84      0.71       47.13         0.00

---------------------------------------------------------------

Total of payments =      1197.84

Total of interest =       197.84

Total to balance  =      1000.00

--------------------------------

 

I basically am so confused on how the calculation works.

[legopc]

dude now you making me all confused  

[qwertywarrior]

will take you  24  months

last month ull pay less than 50

[GBBnero]

                           0.18     x        0.18

          1000 * (1 + ------) ^       * --------

                            12                  12

50 = -------------------------------------------

                             0.18     x        

                       (1 + ------) ^       - 1

                            12                   

 

and then you have to find x

 

basically for your table you go total credit balance at monthly begin + interest rate - payment = credit balance at month end.

And then you just continue from there. I have a script for this but it's in german so it won't help unfortunately  

[SpaceAgentX]

okay like I don't know how to get those numbers. Like the formula. I found a bunch but its always based on a term loan. Like you know how much long it will take but what if you don't know that whats the arithmetic to get that?

[AustinTheIntern]

Linus Financial Tips

 

yey

[SpaceAgentX]

ok I kinda get it. I have to translate that formula into C code. I need to create a amortization table

[GBBnero]

ok I kinda get it. I have to translate that formula into C code. I need to create a amortization table

  

                                  1.18^n - 1

1000 * 1.18^n = 50 * --------------

                                   1.18 - 1

 

[dizmo]

18% is pretty high.

I wouldn't take out a loan at that percentage unless you're seeing income as a result.

[SpaceAgentX]

Thanks GBBnero I'm slowly understanding. So I'm testing on my calculator. I do 1000( 1+ 0.18/12) and i get 1015. now I know I have to take the 15 and subtract it from 50$(the monthly payment) which gives me 35$ that goes towards paying back the 1000 loan and the 15$ goes towards the interest. Right? I'm confused with the math after i get the 1015 value. I'm just trying to figure out how I can translate that into C code once I figure out the arithmetic. 

[Guest]

I can send you my kinda ancient notes on financial maths if you'd like?

[GBBnero]

Thanks GBBnero I'm slowly understanding. So I'm testing on my calculator. I do 1000( 1+ 0.18/12) and i get 1015. now I know I have to take the 15 and subtract it from 50$(the monthly payment) which gives me 35$ that goes towards paying back the 1000 loan and the 15$ goes towards the interest. Right? I'm confused with the math after i get the 1015 value. I'm just trying to figure out how I can translate that into C code once I figure out the arithmetic.

 

 

Yeah just look below I hope this explains it best @ScubaSteve526

 

Uhm so here's the completed amortization table: 

 

 

 

Edit: You are getting 1015 because you currently multiply 1000 by 1 + (0.18/12). If you only want to know how much you pay in interest (not how much interest is added, you simply multiply 1000 by (0.18/12) without the +1. 

So:

 

1000 + (1 * (0.18/12)) = the amount you have to pay currently --> loan + interest rate

1000 + (0.18/12) = only displays the interest rate --> interest rate

Edited February 5, 2014 by GBBnero

[SpaceAgentX]

yea haha anything would be of help at this point

[SirReallySam]

Linus Financial Tips

 

yey

WOW I haven't seen you post in a while Good to see you again...

 

But ummm You probably have been posting.. I just didn't see them

 

Anyways... Man I hate maths.

[AustinTheIntern]

WOW I haven't seen you post in a while Good to see you again...

 

But ummm You probably have been posting.. I just didn't see them

 

Anyways... Man I hate maths.

Hi there sir. Yes I have been caught up with f********* school recently.