Let's break this down. We're going to add 665 and 1207 together.

Step 1: We'll start by adding the digits 5 & 7 in column 1 and get 12.
We'll write down the last digit 2 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 6 & 0 in column 2 and get 7.

Step 3: We'll start by adding the digits 6 & 2 in column 3 and get 8.

Step 4: We'll start by adding the digits 0 & 1 in column 4 and get 1.

So, 665 + 1207 = 1872.

