Okay, let's tackle this math problem. We're starting with 99646 and subtracting 18544.

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

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

Step 3: We'll start by subtracting the digit 5 and the borrow 0 from 6 in column 3 and get 1.
1 is the next digit of our result.

Step 4: We'll start by subtracting the digit 8 and the borrow 0 from 9 in column 4 and get 1.
1 is the next digit of our result.

Step 5: We'll start by subtracting the digit 1 and the borrow 0 from 9 in column 5 and get 8.
8 is the next digit of our result.

So, 99646 - 18544 = 81102.