Okay, we are given 3047 and 3621. Let's add them up step by step.

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 6.

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

So, 3047 + 3621 = 6668.

