Okay, let's tackle this math problem. We're starting with 66802 and subtracting 45302.

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

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

Step 3: We'll start by subtracting the digit 3 and the borrow 0 from 8 in column 3 and get 5.
5 is the next digit of our result.

Step 4: We'll start by subtracting the digit 5 and the borrow 0 from 6 in column 4 and get 1.
1 is the next digit of our result.

Step 5: We'll start by subtracting the digit 4 and the borrow 0 from 6 in column 5 and get 2.
2 is the next digit of our result.

So, 66802 - 45302 = 21500.