Not to worry, we've got 15 and 365. Let's get to adding them!

Step 1: We'll start by adding the digits 5 & 5 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 1 & 6 in column 2 and get 8.

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

So, 15 + 365 = 380.

