Let's get this math done. We have 902904 and 28103, and we're going to subtract the second number from the first.

Step 1: We'll start by subtracting the digit 3 and the borrow 0 from 4 in column 1 and get 1.
1 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 1 and the borrow 0 from 9 in column 3 and get 8.
8 is the next digit of our result.

Step 4: We'll start by subtracting the digit 8 and the borrow 0 from 2 in column 4 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

Step 5: We'll start by subtracting the digit 2 and the borrow 1 from 0 in column 5 and get -3.
We add -3 to 10 and get 7 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, 902904 - 28103 = 874801.