Alright, let's solve this problem step by step. We have 3521 and 6982 and we're adding them together.

Step 1: We'll start by adding the digits 1 & 2 in column 1 and get 3.

Step 2: We'll start by adding the digits 2 & 8 in column 2 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 5 & 9 in column 3 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 3 & 6 in column 4 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 3521 + 6982 = 10503.

