We have numbers 3208 and 3121. Let's start adding them together.

Step 1: We'll start by adding the digits 8 & 1 in column 1 and get 9.

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

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

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

So, 3208 + 3121 = 6329.

