Let's break this down. We're going to add 1404 and 7220 together.

Step 1: We'll start by adding the digits 4 & 0 in column 1 and get 4.

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

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 1 & 7 in column 4 and get 8.

So, 1404 + 7220 = 8624.

