Let's break this down. We're going to add 8754 and 3944 together.

Step 1: We'll start by adding the digits 4 & 4 in column 1 and get 8.

Step 2: We'll start by adding the digits 5 & 4 in column 2 and get 9.

Step 3: We'll start by adding the digits 7 & 9 in column 3 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 8 & 3 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 8754 + 3944 = 12698.

