Okay, we are tasked with adding 12 and 8628. Let's begin!

Step 1: We'll start by adding the digits 2 & 8 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

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

Step 3: We'll start by adding the digits 0 & 6 in column 3 and get 6.

Step 4: We'll start by adding the digits 0 & 8 in column 4 and get 8.

So, 12 + 8628 = 8640.

