Alright, let's solve this problem step by step. We have 121974 and 81206, and we're subtracting the second number from the first.

Step 1: We'll start by subtracting the digit 6 and the borrow 0 from 4 in column 1 and get -2.
We add -2 to 10 and get 8 as the first digit of the result.

Step 2: We'll start by subtracting the digit 0 and the borrow 1 from 7 in column 2 and get 6.
6 is the next digit of our result.

Step 3: We'll start by subtracting the digit 2 and the borrow 0 from 9 in column 3 and get 7.
7 is the next digit of our result.

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

So, 121974 - 81206 = 40768.