Okay, we are tasked with adding 6311 and 6731. Let's begin!

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

Step 2: We'll start by adding the digits 1 & 3 in column 2 and get 4.

Step 3: We'll start by adding the digits 3 & 7 in column 3 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 6 & 6 in column 4 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

So, 6311 + 6731 = 13042.

