Let's break this down. We're going to add 120 and 6119 together.

Step 1: We'll start by adding the digits 0 & 9 in column 1 and get 9.

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

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 0 & 6 in column 4 and get 6.

So, 120 + 6119 = 6239.

