OK, let's do this. We've got 911929 and 12300, and we're subtracting the second number from the first.

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

Step 2: We'll start by subtracting the digit 0 and the borrow 0 from 2 in column 2 and get 2.
2 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 2 and the borrow 0 from 1 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 1 and the borrow 1 from 1 in column 5 and get -1.
We add -1 to 10 and get 9 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, 911929 - 12300 = 899629.