how to calculate cumulative interest

Question

Hello.

i am in need of to calculate following program kindly help me to do.

my project is:

for ex,

april month deposit - 300 (int 9%)

interest - 2.25

may month deposit - 300

existing amount(apr) - 300

total - 600 (9%)

interest - 4.5

sum of int (2.25+4.5) should display in text box. friends i should calculate intrest like this for 12 months
.

my coding is:

int cumu = Convert.ToInt32(textBox3.Text.Trim());

int totdep = Convert.ToInt32(textBox4.Text.Trim());

decimal tot = cumu + totdep;

textBox4.Text = Convert.ToString(tot);

//Decimal subyearly = Convert.ToDecimal(textBox5.Text.Trim());

decimal cumuint = ((tot * 10) / 100)/12;

textBox5.Text = Convert.ToString(cumuint);

actually received amount is textbox3. in textbox4 holds total received in that textbox4 calculating interest. the interest amount will display in textbox5.

my needs are the sum of interest amount should calculate and display in textbox6

how to calculate cumulative interest and the sum of interest should display textbox in c#.net back end is oracle

Thank you in advance..

Vulpes · Answer

The reason I didn't code it like that is because I don't think it's correct in principle. When the new deposit is received the existing deposits have accrued one month's interest. However the new deposit won't accrue any interest until the following month when interest will be calculated on the total deposits shown in textBox4. If despite this you still want to accrue interest on the new deposit as soon as it's received then change this line: decimal cumuint = cumu * 9m/ 1200m; // interest for a month at 9% on cumulative deposits before new one to this one: decimal cumuint = tot * 9m/ 1200m; // interest for a month at 9% on total deposits including the new one

Vulpes · Answer

If I've understood it properly (which I may not have done) then try this: int cumu = Convert.ToInt32(textBox3.Text.Trim()); // cumulative deposits before new deposit added int dep = Convert.ToInt32(textBox4.Text.Trim()); // new monthly deposit (no interest earned yet) decimal tot = cumu + dep; // total deposits to date textBox4.Text = Convert.ToString(tot); decimal cumuint = cumu * 9m/ 1200m; // interest for a month at 9% on cumulative deposits before new one textBox5.Text = Convert.ToString(cumuint); decimal totint = Convert.ToDecimal(textBox6.Text.Trim()); // total interest before new interest added totint += cumuint; textBox6.Text = Convert.ToString(totint); // total interest to date

LOGANATHAN V · Answer

thank you friend. now no problem for my coding

Vulpes · Answer

OK I've looked at the Excel spreadsheet and it does as you say calculate interest on the total deposits including the new one. I guess that would make sense if the deposit is always paid at the beginning of each month but interest is calculated at the end of each month. So I'd therefore incorporate the amendment in my previous post into your code.

LOGANATHAN V · Answer

hello friend i have attached excel book for sample calculation. kindly refer it

LOGANATHAN V · Answer

so far this is right. but the previous interest is 2.25 new ie second deposit interest is 4.25 so the total interest is 6.5 is should display. your coding is almost okay the sum of total int calculation is missing