Okay, we are tasked with adding 31 and 345. Let's begin!

Step 1: We'll start by adding the digits 1 & 5 in column 1 and get 6.

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 0 & 3 in column 3 and get 3.

So, 31 + 345 = 376.

