We can solve this together! We're beginning with 855981 and removing 42071 from it.

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

Step 2: We'll start by subtracting the digit 7 and the borrow 0 from 8 in column 2 and get 1.
1 is the next digit of our result.

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

Step 4: We'll start by subtracting the digit 2 and the borrow 0 from 5 in column 4 and get 3.
3 is the next digit of our result.

Step 5: We'll start by subtracting the digit 4 and the borrow 0 from 5 in column 5 and get 1.
1 is the next digit of our result.

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

So, 855981 - 42071 = 813910.