Okay, let's tackle this math problem. We're starting with 98866 and subtracting 12819.

Step 1: We'll start by subtracting the digit 9 and the borrow 0 from 6 in column 1 and get -3.
We add -3 to 10 and get 7 as the first digit of the result.

Step 2: We'll start by subtracting the digit 1 and the borrow 1 from 6 in column 2 and get 4.
4 is the next digit of our result.

Step 3: We'll start by subtracting the digit 8 and the borrow 0 from 8 in column 3 and get 0.
0 is the next digit of our result.

Step 4: We'll start by subtracting the digit 2 and the borrow 0 from 8 in column 4 and get 6.
6 is the next digit of our result.

Step 5: We'll start by subtracting the digit 1 and the borrow 0 from 9 in column 5 and get 8.
8 is the next digit of our result.

So, 98866 - 12819 = 86047.