We have numbers 3351 and 2004. Let's start adding them together.

Step 1: We'll start by adding the digits 1 & 4 in column 1 and get 5.

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

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

Step 4: We'll start by adding the digits 3 & 2 in column 4 and get 5.

So, 3351 + 2004 = 5355.

