Multiplication using recursion

Jonathan Crispe

i have this value and know how to calculate it but i don't know how to put in a recursion code.
Any advice pls...Thank you

the amount $10000
the interest rate 10%
the investment period 10 years
the total value would $25, 937.42

main calls Ryear(10) return 23579.47
n = 10 return 23579.47 * 1.1
n = 9 return 21435.89 * 1.1
n = 8 return 19487.17 * 1.1
n = 7 return 17715.61 * 1.1
n = 6 return 16105.1 * 1.1
n = 5 return 14641 * 1.1
n = 4 return 13310 * 1.1
n = 3 return 12100 * 1.1
n = 2 return 11000 * 1.1
n = 1 return 10000 * 1.1
n = 0 Return 10000

this just is the example i got from my class...
static void Main(string[] args)
{
    Console.WriteLine(Ryear(10));
    Console.ReadLine();
}
static private int Ryear(int n)
{
      int amount = 10000;
      int
      if (n < 1)
             return 0;
      else
      return Ryear(n-1)+ n;
}

9 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
Although Karthik's code works, he's used iteration rather than recursion to calculate the accumulated amount.

Adjusting his code to use recursion, gives us the following:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace interest_calculation
{
class Program
{
static void Main(string[] args)
{
while (true)
{
float principal_amount = 0;
int no_of_yrs = 0;
int interest_rate = 0;
Console.Write("Please Enter the principal amount (0 to exit) : ");
principal_amount = Convert.ToInt32(Console.ReadLine());
if(principal_amount == 0) return;
Console.WriteLine();
Console.Write("Please Enter the years you want to deposit for : ");
no_of_yrs = Convert.ToInt32(Console.ReadLine());
Console.WriteLine();
Console.Write("Please Enter the interest rate : ");
interest_rate = Convert.ToInt32(Console.ReadLine());
Console.WriteLine();
float final_amount = AccumulateAmount(principal_amount, no_of_yrs, interest_rate);
Console.WriteLine("Your final returns are : " + Convert.ToString(final_amount));
Console.WriteLine();
}
}

static float AccumulateAmount(float amount, int years, int rate)
{
if (years < 1) return amount;
amount += amount/100 * rate;
return AccumulateAmount(amount, years - 1, rate);
}
}
}
Vulpes14y ago
It's because amount is now of type int rather rather than float or double.

Consequently, when you divide it by 100, integer rather than floating point arithmetic will be used and you'll lose some accuracy in the final result.

I'd therefore change amount to double even if you only intend to input integers.
Jonathan Crispe14y ago
i tried to convert the code from console to windows forms. except i didn't use the float,
its just double and int.

public Form1()
{
InitializeComponent();
}

int m_amount, m_rate, m_years;
double m_total = 0;

private void btnCALCULATE_Click(object sender, EventArgs e)
{
m_amount = int.Parse(tbAMOUNT.Text);
m_rate = int.Parse(tbRATE.Text);
m_years = (int)numYEARS.Value;
m_total = Recursion(m_amount, m_rate, m_years);

tbFUTUREVALUE.Text = m_total.ToString("C2");
}

static double Recursion(int amount, int years, int rate)
{
if (years < 1) return amount;
amount += amount / 100 * rate;
return Recursion(amount, years - 1, rate);
}
}

it works but wrong calculation:
i put the same value: 10000 amount, 10 interest rate, 10 in investment period. the difference is the future value.
the future value : $25, 910.00 instead of $25, 937.42
Vulpes14y ago
It is and nobody would do this using recursion in practice.

However, he specifically asked for it to be done using recursion as it's no doubt a school/college exercise in programming techniques.
Karthik Agarwal14y ago
But the result is one and only the same right?

Karthik Agarwal14y ago

Let me know the status whether it's working or not after you check that out.

If you find my post helpful, Mark it as Answered or Rate the post.

Karthik Agarwal14y ago
this is whole code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace interest_calculation
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                float principal_amount = 0;
                int no_of_yrs = 0;
                int interest_rate = 0;
                float final_amount = 0;
                Console.Write("Please Enter the principal amount : ");
                principal_amount = Convert.ToInt32(Console.ReadLine());
                Console.WriteLine();
                Console.Write("Please Enter the years you want to deposit for : ");
                no_of_yrs = Convert.ToInt32(Console.ReadLine());
                Console.WriteLine();
                Console.Write("Please Enter the interest rate : ");
                interest_rate = Convert.ToInt32(Console.ReadLine());
                Console.WriteLine();

                for (int i = 0; i < no_of_yrs; i++)
                {
                    final_amount = principal_amount + ((principal_amount / 100) * interest_rate);
                    principal_amount = final_amount;
                }
                Console.WriteLine("Your final returns are : " + Convert.ToString(final_amount));
                Console.ReadLine();
            }
        }
    }
}
Jonathan Crispe14y ago
ignore the int amount in the code...

I'm will trying to display the final answer using recursion code...

Any number in principal amount and interest rate.
The range will be 1 to 100, representing the years of investment.
The calculated interest will be added to the principal value once every period (year).

example:
Lets put 10000 in principal amount and 10% in interest rate and
And 10 in years of investment.

The calculation would be this:

10000 * 1.1 = 11000 or ((10000 * 0.1) + 10000)
11000 * 1.1 = 12100 or ((11000 * 0.1) + 11000)
12100 * 1.1 = . . . .
. . . . * 1.1 = 25, 937.42

finally would be $25, 937.42
Karthik Agarwal14y ago
Can you please explain in detail what you are trying to do? Are you trying to get number of years from console window and trying to display the calculated interest along with the principle amount back in console window or what? If so can the years be more or less than 10 or else is the years fixed to 10? Explain your requirements in detail so that anyone can come up with an exact solution.