Okay, we are tasked with adding 6012 and 3480. Let's begin!

Step 1: We'll start by adding the digits 2 & 0 in column 1 and get 2.

Step 2: We'll start by adding the digits 1 & 8 in column 2 and get 9.

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 6 & 3 in column 4 and get 9.

So, 6012 + 3480 = 9492.

