Let's break this down. We're going to add 2712 and 2905 together.

Step 1: We'll start by adding the digits 2 & 5 in column 1 and get 7.

Step 2: We'll start by adding the digits 1 & 0 in column 2 and get 1.

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 2 & 2 in column 4 and get 5.

So, 2712 + 2905 = 5617.

