Let's break this down. We're going to add 9812 and 685 together.

Step 1: We'll start by adding the digits 2 & 5 in column 1 and get 7.

Step 2: We'll start by adding the digits 1 & 8 in column 2 and get 9.

Step 3: We'll start by adding the digits 8 & 6 in column 3 and get 14.
We'll write down the last digit 4 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 9 & 0 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 9812 + 685 = 10497.

