Not to worry, we've got 9923 and 2812. Let's get to adding them!

Step 1: We'll start by adding the digits 3 & 2 in column 1 and get 5.

Step 2: We'll start by adding the digits 2 & 1 in column 2 and get 3.

Step 3: We'll start by adding the digits 9 & 8 in column 3 and get 17.
We'll write down the last digit 7 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 9 & 2 in column 4 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

So, 9923 + 2812 = 12735.

