Let's break this down. We're going to add 1217 and 1091 together.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

Step 2: We'll start by adding the digits 1 & 9 in column 2 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 2 & 0 in column 3 and get 3.

Step 4: We'll start by adding the digits 1 & 1 in column 4 and get 2.

So, 1217 + 1091 = 2308.

