Not to worry, we've got 663 and 6000. Let's get to adding them!

Step 1: We'll start by adding the digits 3 & 0 in column 1 and get 3.

Step 2: We'll start by adding the digits 6 & 0 in column 2 and get 6.

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

Step 4: We'll start by adding the digits 0 & 6 in column 4 and get 6.

So, 663 + 6000 = 6663.

