Not to worry, we've got 4002 and 5306. Let's get to adding them!

Step 1: We'll start by adding the digits 2 & 6 in column 1 and get 8.

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

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

Step 4: We'll start by adding the digits 4 & 5 in column 4 and get 9.

So, 4002 + 5306 = 9308.

