Let's break this down. We're going to add 337 and 513 together.

Step 1: We'll start by adding the digits 7 & 3 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 3 & 1 in column 2 and get 5.

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

So, 337 + 513 = 850.

