Got it! So, we have 913173 and 64042, and we'll subtract the latter from the former.

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

Step 2: We'll start by subtracting the digit 4 and the borrow 0 from 7 in column 2 and get 3.
3 is the next digit of our result.

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

Step 4: We'll start by subtracting the digit 4 and the borrow 0 from 3 in column 4 and get -1.
We add -1 to 10 and get 9 as the next digit of the result.

Step 5: We'll start by subtracting the digit 6 and the borrow 1 from 1 in column 5 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

Step 6: We'll start by subtracting the digit 0 and the borrow 1 from 9 in column 6 and get 8.
8 is the next digit of our result.

So, 913173 - 64042 = 849131.