Java method to calculate the square root via minuend and subtrahend and print each step

Question

I am tasked with creating a program in java which calculates the square root of a double and goes through each step of calculating it manually. The requirements are:

1. split the number into number pairs including the decimal point (1234.67 -> 12 34 67) to prepare for subtraction. If the number is uneven, a zero must populate (234.67 -> 02 34 67)
2. Print each pair (each pair is a minuend), one at a time, into the console and have the console show the subtraction. Subtrahend starts at 1 and so long as the result >= 0, the subtrahend increases by 2.
3. The count of subtrahends is the first number of the final square root output, the count of subtrahends from the second round is the second number of the square root output, etc.
4. From the first subtrahend round, take the remainder and join it to the second number pair, this is the new minuend for the second round of subtraction
5. Calculate the second subtrahend in round two by doubling the first number of the square root output and adding 1 in the first digit position
6. Repeat step 2, increasing by 2 each time
7. Step 5 and 6 repeat until two decimal places are reached

My question is with the number pairs in step 1 and getting the subsequent subtrahends after step 3 as a number to calculate. We are given the following visual:

My current thought is to put the double into a string and then tell java that each number pair is a number. I have a method created which creates a string from a double, but I am still missing how to incorporate the decimal place numbers. From my C class, I remember multiplying decimals by 100 to "store" the decimal numbers before converting them back later with another division by 100. I'm sure there is a java library that is able to do this but we are specifically not allowed to use them.

I think I should be able to continue on with the rest of the problem once I get past this point of splitting the number into number pairs inclusive of the decimals.

This is also my first stack post so if you have any tips on how to better write questions for future posts that would be helpful as well.

This is my current array method to store a given double into an array:

public static void printArray(int [] a) //printer helper method
{
   for(int i = 0; i < a.length; i++)
   {
      System.out.print(a[i]);
   }
}

public static void stringDigits (double n) //begin string method
{
   int a [] = new int [15];
   int i = 0;
   int stringLength = 0;

   while(n > 1)
   {
      a[i] = (int) (n % 10);
      n = n / 10;
      i++;
   }

   for(int j = 0; a[j] != 0; j++)
   {
      System.out.print(a[j]);
      if(a[j] != 0)
      {
         stringLength++;
      }
   }

   System.out.println("");
   System.out.println(stringLength);

   int[] numbersArray = new int[stringLength];
   int g = 0;

   for(int k = a.length-1; g < numbersArray.length; k--)
   {
      if(a[k] > 0)
      {
         numbersArray[g] = a[k];
         g++;
      }
   }
   System.out.println("");
   printArray(numbersArray);
   
}

I've tried at first to store the value of the double into an int[] a array so that I can then select the numbers in pairs and then somehow combine them back into numbers. So if the array is {1,2,3,4,5,6} my next idea is to get java to convert a[0] + a[1] into the number 12 to prepare for the subtraction step.

This link looks close but does anyone know why the numbers are "10l" and "100l" etc? I've tested some of the answers and they dont produce the proper squareroot compared to the sqrt function from the math library.

Create a program that calculates the square root of a number without using Math.sqrt