Okay, we are tasked with adding 8538 and 20. Let's begin!

Step 1: We'll start by adding the digits 8 & 0 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 5 & 0 in column 3 and get 5.

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

So, 8538 + 20 = 8558.

