Alright, let's solve this problem step by step. We have 993199963 and 154506327, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 7 and the borrow 0 from 3 in column 1 and get -4.
We add -4 to 10 and get 6 as the first digit of the result.

Step 2: We'll start by subtracting the digit 2 and the borrow 1 from 6 in column 2 and get 3.
3 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 6 and the borrow 0 from 9 in column 4 and get 3.
3 is the next digit of our result.

Step 5: We'll start by subtracting the digit 0 and the borrow 0 from 9 in column 5 and get 9.
9 is the next digit of our result.

Step 6: We'll start by subtracting the digit 5 and the borrow 0 from 1 in column 6 and get -4.
We add -4 to 10 and get 6 as the next digit of the result.

Step 7: We'll start by subtracting the digit 4 and the borrow 1 from 3 in column 7 and get -2.
We add -2 to 10 and get 8 as the next digit of the result.

Step 8: We'll start by subtracting the digit 5 and the borrow 1 from 9 in column 8 and get 3.
3 is the next digit of our result.

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

So, 993199963 - 154506327 = 838693636.