We have numbers 58 and 809. Let's start adding them together.

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

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 6.

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

So, 58 + 809 = 867.

