Alright, let's solve this problem step by step. We have 21500 and 21500, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 0 and the borrow 0 from 0 in column 1 and get 0.
0 is the first digit of our result.

Step 2: We'll start by subtracting the digit 0 and the borrow 0 from 0 in column 2 and get 0.
0 is the next digit of our result.

Step 3: We'll start by subtracting the digit 5 and the borrow 0 from 5 in column 3 and get 0.
0 is the next digit of our result.

Step 4: We'll start by subtracting the digit 1 and the borrow 0 from 1 in column 4 and get 0.
0 is the next digit of our result.

Step 5: We'll start by subtracting the digit 2 and the borrow 0 from 2 in column 5 and get 0.
0 is the next digit of our result.

So, 21500 - 21500 = 0.