Let's break this down. We're going to add 3562 and 8220 together.

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

Step 2: We'll start by adding the digits 6 & 2 in column 2 and get 8.

Step 3: We'll start by adding the digits 5 & 2 in column 3 and get 7.

Step 4: We'll start by adding the digits 3 & 8 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 3562 + 8220 = 11782.

