Not to worry, we've got 1215 and 1513. Let's get to adding them!

Step 1: We'll start by adding the digits 5 & 3 in column 1 and get 8.

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

Step 3: We'll start by adding the digits 2 & 5 in column 3 and get 7.

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

So, 1215 + 1513 = 2728.

