Okay, let's tackle this math problem. We're starting with 83843 and subtracting 43842.

Step 1: We'll start by subtracting the digit 2 and the borrow 0 from 3 in column 1 and get 1.
1 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 8 and the borrow 0 from 8 in column 3 and get 0.
0 is the next digit of our result.

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

Step 5: We'll start by subtracting the digit 4 and the borrow 0 from 8 in column 5 and get 4.
4 is the next digit of our result.

So, 83843 - 43842 = 40001.