Let's break this down. We're going to add 131 and 11 together.

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

Step 2: We'll start by adding the digits 3 & 1 in column 2 and get 4.

Step 3: We'll start by adding the digits 1 & 0 in column 3 and get 1.

So, 131 + 11 = 142.

