Let's break this down. We're going to add 6478 and 2406 together.

Step 1: We'll start by adding the digits 8 & 6 in column 1 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 7 & 0 in column 2 and get 8.

Step 3: We'll start by adding the digits 4 & 4 in column 3 and get 8.

Step 4: We'll start by adding the digits 6 & 2 in column 4 and get 8.

So, 6478 + 2406 = 8884.

