Okay, we are tasked with adding 331 and 633. Let's begin!

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

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

Step 3: We'll start by adding the digits 3 & 6 in column 3 and get 9.

So, 331 + 633 = 964.

