We have numbers 5803 and 3009. Let's start adding them together.

Step 1: We'll start by adding the digits 3 & 9 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 0 in column 2 and get 1.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

Step 4: We'll start by adding the digits 5 & 3 in column 4 and get 8.

So, 5803 + 3009 = 8812.

