Let's break this down. We're going to add 8520 and 3247 together.

Step 1: We'll start by adding the digits 0 & 7 in column 1 and get 7.

Step 2: We'll start by adding the digits 2 & 4 in column 2 and get 6.

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 8 & 3 in column 4 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

So, 8520 + 3247 = 11767.

