Here we go! We're going to add 666 and 2331 together.

Step 1: We'll start by adding the digits 6 & 1 in column 1 and get 7.

Step 2: We'll start by adding the digits 6 & 3 in column 2 and get 9.

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

Step 4: We'll start by adding the digits 0 & 2 in column 4 and get 2.

So, 666 + 2331 = 2997.

