getting ArgumentOutOfRangeException for my custom data type.

Question

I am getting this error at "get => (JaggedData)jaggeddatas[index];". Please direct me to the right direction towards the solution.

class JaggedDataCollection
{
ArrayList jaggeddatas = new ArrayList();
public JaggedData this[int index]
{
get => (JaggedData)jaggeddatas[index];
set => jaggeddatas.Insert(index, value);
}
}
public class NumberWithDifference
{
public int Number { get; set; }
public static int[] decimalNumbers = new int[10]{0,1,2,3,4,5,6,7,8,9};
JaggedDataCollection jdc = new JaggedDataCollection();
foreach (var item in jagged.Items)
{
i = true;
int index = 0;
bool i = true;
int index = 0;
for (int j = 0; j < decimalNumbers.Length; j++)
{
if (jdc[index].Number == decimalNumbers[j])
{
Console.Write(decimalNumbers[j]);
i = false;
if (index < decimalNumbers.Length - 1)
index++;
} else
{ Console.Write(0); }
}
}
}

This is the error I am getting "System.ArgumentOutOfRangeException"