Let's break this down. We're going to add 8305 and 685 together.

Step 1: We'll start by adding the digits 5 & 5 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 8 in column 2 and get 9.

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

Step 4: We'll start by adding the digits 8 & 0 in column 4 and get 8.

So, 8305 + 685 = 8990.

