Let's break this down. We're going to add 7640 and 1338 together.

Step 1: We'll start by adding the digits 0 & 8 in column 1 and get 8.

Step 2: We'll start by adding the digits 4 & 3 in column 2 and get 7.

Step 3: We'll start by adding the digits 6 & 3 in column 3 and get 9.

Step 4: We'll start by adding the digits 7 & 1 in column 4 and get 8.

So, 7640 + 1338 = 8978.

