Okay, we are tasked with adding 8520 and 1053. Let's begin!

Step 1: We'll start by adding the digits 0 & 3 in column 1 and get 3.

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

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 & 1 in column 4 and get 9.

So, 8520 + 1053 = 9573.

