Got it! So, we have 640098 and 50606, and we'll subtract the latter from the former.

Step 1: We'll start by subtracting the digit 6 and the borrow 0 from 8 in column 1 and get 2.
2 is the first digit of our result.

Step 2: We'll start by subtracting the digit 0 and the borrow 0 from 9 in column 2 and get 9.
9 is the next digit of our result.

Step 3: We'll start by subtracting the digit 6 and the borrow 0 from 0 in column 3 and get -6.
We add -6 to 10 and get 4 as the next digit of the result.

Step 4: We'll start by subtracting the digit 0 and the borrow 1 from 0 in column 4 and get -1.
We add -1 to 10 and get 9 as the next digit of the result.

Step 5: We'll start by subtracting the digit 5 and the borrow 1 from 4 in column 5 and get -2.
We add -2 to 10 and get 8 as the next digit of the result.

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

So, 640098 - 50606 = 589492.