Okay, let's tackle this math problem. We're starting with 3881 and subtracting 1261.

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

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

Step 3: We'll start by subtracting the digit 2 and the borrow 0 from 8 in column 3 and get 6.
6 is the next digit of our result.

Step 4: We'll start by subtracting the digit 1 and the borrow 0 from 3 in column 4 and get 2.
2 is the next digit of our result.

So, 3881 - 1261 = 2620.