OK, let's do this. We've got 85939 and 81927, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 7 and the borrow 0 from 9 in column 1 and get 2.
2 is the first digit of our result.

Step 2: We'll start by subtracting the digit 2 and the borrow 0 from 3 in column 2 and get 1.
1 is the next digit of our result.

Step 3: We'll start by subtracting the digit 9 and the borrow 0 from 9 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 5 in column 4 and get 4.
4 is the next digit of our result.

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

So, 85939 - 81927 = 4012.