Let's solve this addition problem. We have 6335 and 1021, and we need to add them together.

Step 1: We'll start by adding the digits 5 & 1 in column 1 and get 6.

Step 2: We'll start by adding the digits 3 & 2 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 6 & 1 in column 4 and get 7.

So, 6335 + 1021 = 7356.

