Alright, let's solve this problem step by step. We have 924121 and 81785, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 5 and the borrow 0 from 1 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 8 and the borrow 1 from 2 in column 2 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

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

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

Step 5: We'll start by subtracting the digit 8 and the borrow 0 from 2 in column 5 and get -6.
We add -6 to 10 and get 4 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, 924121 - 81785 = 842336.