Okay, we are tasked with adding 1017 and 5421. Let's begin!

Step 1: We'll start by adding the digits 7 & 1 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 0 & 4 in column 3 and get 4.

Step 4: We'll start by adding the digits 1 & 5 in column 4 and get 6.

So, 1017 + 5421 = 6438.

