Let's break this down. We're going to add 2403 and 4274 together.

Step 1: We'll start by adding the digits 3 & 4 in column 1 and get 7.

Step 2: We'll start by adding the digits 0 & 7 in column 2 and get 7.

Step 3: We'll start by adding the digits 4 & 2 in column 3 and get 6.

Step 4: We'll start by adding the digits 2 & 4 in column 4 and get 6.

So, 2403 + 4274 = 6677.

