No problem, let's work through this together. We're starting with 1021 and 3963 and adding them all up.

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 2 & 6 in column 2 and get 8.

Step 3: We'll start by adding the digits 0 & 9 in column 3 and get 9.

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

So, 1021 + 3963 = 4984.

