Okay, we are tasked with adding 3351 and 5223. Let's begin!

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

Step 2: We'll start by adding the digits 5 & 2 in column 2 and get 7.

Step 3: We'll start by adding the digits 3 & 2 in column 3 and get 5.

Step 4: We'll start by adding the digits 3 & 5 in column 4 and get 8.

So, 3351 + 5223 = 8574.

