Okay, we are tasked with adding 2331 and 1240. Let's begin!

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

Step 2: We'll start by adding the digits 3 & 4 in column 2 and get 7.

Step 3: We'll start by adding the digits 3 & 2 in column 3 and get 5.

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

So, 2331 + 1240 = 3571.

