Let's break this down. We're going to add 2641 and 6358 together.

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

Step 2: We'll start by adding the digits 4 & 5 in column 2 and get 9.

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 2 & 6 in column 4 and get 8.

So, 2641 + 6358 = 8999.

