Let's break this down. We're going to add 142 and 8321 together.

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

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

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 0 & 8 in column 4 and get 8.

So, 142 + 8321 = 8463.

