Let's break this down. We're going to add 9003 and 7055 together.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

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

Step 4: We'll start by adding the digits 9 & 7 in column 4 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

So, 9003 + 7055 = 16058.

