Let's break this down. We're going to add 1117 and 8139 together.

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

Step 2: We'll start by adding the digits 1 & 3 in column 2 and get 5.

Step 3: We'll start by adding the digits 1 & 1 in column 3 and get 2.

Step 4: We'll start by adding the digits 1 & 8 in column 4 and get 9.

So, 1117 + 8139 = 9256.

