Let's break this down. We're going to add 213 and 300 together.

Step 1: We'll start by adding the digits 3 & 0 in column 1 and get 3.

Step 2: We'll start by adding the digits 1 & 0 in column 2 and get 1.

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

So, 213 + 300 = 513.

