Okay, we are tasked with adding 3251 and 3209. Let's begin!

Step 1: We'll start by adding the digits 1 & 9 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 5 & 0 in column 2 and get 6.

Step 3: We'll start by adding the digits 2 & 2 in column 3 and get 4.

Step 4: We'll start by adding the digits 3 & 3 in column 4 and get 6.

So, 3251 + 3209 = 6460.

