Understanding the String Rotation

The problem asks us to modify a given string by performing a specific rotation. We need to take the last 10 letters (characters) of the string and move them to become the first 10 letters, effectively rotating the string. After rearranging the string, the goal is to determine the number of letters that appear between the character 'B' and the character 'D' in the newly formed string.

Analyzing the Original String

The initial string provided is:

T W E K D P S L Z U B Y S Q N R G J

First, let's count the total number of characters in this string. Counting carefully, we find there are 18 characters in total.

Performing the String Transformation

The core task is to rearrange the string by moving the last 10 characters to the beginning.

• Step 1: Identify the last 10 letters.
  From the original string "T W E K D P S L Z U B Y S Q N R G J", the last 10 characters are:
  Z U B Y S Q N R G J
• Step 2: Identify the remaining letters.
  The characters that come before these last 10 are the first 8 characters of the original string:
  T W E K D P S L
• Step 3: Construct the new string.
  By placing the identified last 10 characters at the very beginning, followed by the first 8 characters, the transformed string is formed:
  Z U B Y S Q N R G J T W E K D P S L

Locating 'B' and 'D' in the New String

Now, we need to examine the transformed string to find the positions of the letters 'B' and 'D'.

The transformed string is: Z U B Y S Q N R G J T W E K D P S L

We can observe the positions (using 0-based indexing):

• The letter 'B' is located at index 2.
• The letter 'D' is located at index 14.

Counting Letters Between 'B' and 'D'

The final step is to count how many letters are strictly between 'B' and 'D' in the rearranged string.

The letters situated between 'B' (at index 2) and 'D' (at index 14) are:

Y S Q N R G J T W E K

To calculate the number of letters between these two positions, we can subtract the index of 'B' from the index of 'D' and then subtract 1 (to exclude 'B' and 'D' themselves).

The calculation is: (Index of 'D') - (Index of 'B') - 1.

Using the indices we found: $(14 - 2) - 1 = 12 - 1 = 11$.

Therefore, there are exactly '$11$' letters between 'B' and 'D' in the modified string.