while loops with compound interest

hello, i am trying to work out a problem that i am having with while loops. i have to determine how much to save each month in order to reach a goal of 100836 in 216 months. the interest rate is 5.5 per year. so far, i have written the following script but the number does not seem believable to me.

%minimum deposit in 18 years

n=18*12;

balance= 2000;

deposit=200;

while balance<100836.46

      balance=balance*(1+(5.5/1200))+deposit;

      deposit=deposit+50+(20*n);

end

disp(deposit)

disp(balance)

i end up getting an odd number which is 35160. i think that the number should be in the 200's assuming that the initial deposit is 200.

[Star Strider]

Duplicate of: http://www.mathworks.com/matlabcentral/answers/252403-while-for-loops-in-deposit-calculations

[Astha Sharma]

i asked both questions

[Walter Roberson]

When you ask the same question multiple times, the volunteers end up spending their time finding and merging the multiple questions, instead of spending their time answering questions.

Answer 1

[Walter Roberson]

Why are you adding (20*n) each deposit period?

[Astha Sharma]

i have reworked the problem to be:

balance(1)=2000;

deposit(1)=250;

while balance(b1)<=100836

deposit=deposit+10;

for b1=1:216

balance(b1)=(balance(b1-1)*(1+(5.5/1200))+deposit);

end

end

but this is still not giving me the answer i am looking for.

[Walter Roberson]

initialize
while true
  do a calculation
  if we succeeded
    break;
  end
  change the variables for the next try
end