Let's break this down. We're going to add 8712 and 1234 together.

Step 1: We'll start by adding the digits 2 & 4 in column 1 and get 6.

Step 2: We'll start by adding the digits 1 & 3 in column 2 and get 4.

Step 3: We'll start by adding the digits 7 & 2 in column 3 and get 9.

Step 4: We'll start by adding the digits 8 & 1 in column 4 and get 9.

So, 8712 + 1234 = 9946.

