Alright, ready to do some subtraction? We're taking 378686 and subtracting 71800 from it.

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

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

Step 3: We'll start by subtracting the digit 8 and the borrow 0 from 6 in column 3 and get -2.
We add -2 to 10 and get 8 as the next digit of the result.

Step 4: We'll start by subtracting the digit 1 and the borrow 1 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 7 and the borrow 0 from 7 in column 5 and get 0.
0 is the next digit of our result.

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

So, 378686 - 71800 = 306886.