Alright, let's solve this problem step by step. We have 868980 and 51318, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 8 and the borrow 0 from 0 in column 1 and get -8.
We add -8 to 10 and get 2 as the first digit of the result.

Step 2: We'll start by subtracting the digit 1 and the borrow 1 from 8 in column 2 and get 6.
6 is the next digit of our result.

Step 3: We'll start by subtracting the digit 3 and the borrow 0 from 9 in column 3 and get 6.
6 is the next digit of our result.

Step 4: We'll start by subtracting the digit 1 and the borrow 0 from 8 in column 4 and get 7.
7 is the next digit of our result.

Step 5: We'll start by subtracting the digit 5 and the borrow 0 from 6 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, 868980 - 51318 = 817662.