Alright, let's solve this problem step by step. We have 3143 and 3355 and we're adding them together.

Step 1: We'll start by adding the digits 3 & 5 in column 1 and get 8.

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

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

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

So, 3143 + 3355 = 6498.

