Let's break this down. We're going to add 3904 and 3037 together.

Step 1: We'll start by adding the digits 4 & 7 in column 1 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 0 & 3 in column 2 and get 4.

Step 3: We'll start by adding the digits 9 & 0 in column 3 and get 9.

Step 4: We'll start by adding the digits 3 & 3 in column 4 and get 6.

So, 3904 + 3037 = 6941.

