Let's break this down. We're going to add 8600 and 1090 together.

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

Step 2: We'll start by adding the digits 0 & 9 in column 2 and get 9.

Step 3: We'll start by adding the digits 6 & 0 in column 3 and get 6.

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

So, 8600 + 1090 = 9690.

